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diff --git a/.gitattributes b/.gitattributes new file mode 100644 index 0000000..d7b82bc --- /dev/null +++ b/.gitattributes @@ -0,0 +1,4 @@ +*.txt text eol=lf +*.htm text eol=lf +*.html text eol=lf +*.md text eol=lf diff --git a/LICENSE.txt b/LICENSE.txt new file mode 100644 index 0000000..6312041 --- /dev/null +++ b/LICENSE.txt @@ -0,0 +1,11 @@ +This eBook, including all associated images, markup, improvements, +metadata, and any other content or labor, has been confirmed to be +in the PUBLIC DOMAIN IN THE UNITED STATES. + +Procedures for determining public domain status are described in +the "Copyright How-To" at https://www.gutenberg.org. + +No investigation has been made concerning possible copyrights in +jurisdictions other than the United States. Anyone seeking to utilize +this eBook outside of the United States should confirm copyright +status under the laws that apply to them. diff --git a/README.md b/README.md new file mode 100644 index 0000000..e86666d --- /dev/null +++ b/README.md @@ -0,0 +1,2 @@ +Project Gutenberg (https://www.gutenberg.org) public repository for +eBook #62677 (https://www.gutenberg.org/ebooks/62677) diff --git a/old/62677-8.txt b/old/62677-8.txt deleted file mode 100644 index 15fa12b..0000000 --- a/old/62677-8.txt +++ /dev/null @@ -1,3070 +0,0 @@ -The Project Gutenberg EBook of USDA Bulletin No. 816, by F. L. Mulford - -This eBook is for the use of anyone anywhere in the United States and most -other parts of the world at no cost and with almost no restrictions -whatsoever. You may copy it, give it away or re-use it under the terms of -the Project Gutenberg License included with this eBook or online at -www.gutenberg.org. If you are not located in the United States, you'll have -to check the laws of the country where you are located before using this ebook. - -Title: USDA Bulletin No. 816 - Street Trees - -Author: F. L. Mulford - -Release Date: July 16, 2020 [EBook #62677] - -Language: English - -Character set encoding: ISO-8859-1 - -*** START OF THIS PROJECT GUTENBERG EBOOK USDA BULLETIN NO. 816 *** - - - - -Produced by Tom Cosmas - - - - - - - - -Transcriber Note - - Whole and fractional parts are shown as 2-1/2. - Emphasis shown as _Italics_ and =Bold=. - - - - - UNITED STATES DEPARTMENT OF AGRICULTURE - - =BULLETIN No. 816= - - Contribution from the Bureau of Plant Industry - - Wm. A. Taylor, Chief - - - ------------------------------------------------------- - Washington, D. C. [Illustration] January 19, 1920 - ------------------------------------------------------- - - - - =STREET TREES= - - - By - - - =F. L. MULFORD, Horticulturist= - - - Office of Horticultural and - Pomological Investigations - - ------------------------------------------------------- - - - - CONTENTS - - - Page - - Importance of Shade Trees 1 - - Public Control of Street Trees 6 - - Planning for Trees on City Streets 8 - - Spacing Trees 9 - - Conditions for Tree Growth 10 - - Kinds of Trees Suitable for City Streets 14 - Qualities Necessary 14 - Trees for Different Regions 16 - Trees for Special Purposes 20 - - Descriptions of Street Trees 20 - - Culture of Street Trees 43 - Selection of Individual Trees 43 - Preparation of Holes 44 - Planting 45 - Pruning 50 - Stakes and Guards 51 - Later Care 52 - - Care of Mature Trees 53 - Pruning 53 - Feeding 55 - Spraying 55 - - - [Illustration] - - - WASHINGTON - GOVERNMENT PRINTING OFFICE - - 1920 - - -=BUREAU OF PLANT INDUSTRY.= - - William A. Taylor, _Chief_. - K. F. Kellerman, _Associate Chief_. - James E. Jones, _Assistant to Chief_. - J. E. Rockwell, _Officer in Charge of Publications_. - - -Office of Horticultural and Pomological Investigations. - -SCIENTIFIC STAFF. - - L. C. Corbett, _Horticulturist in Charge_. - - -Truck Crop Production Investigations: - - J. H. Beattie. - F. E. Miller. - C. J. Hunn. - B. J. McGervey. - -Irish Potato Production Investigations: - - William Stuart. - C. F. Clark. - W. C. Edmundson. - P. M. Lombard. - J. W. Wellington. - L. L. Corbett. - -Truck Crop Improvement Investigations: - - W. W. Tracy. - D. N. Shoemaker. - -Landscape Gardening and Floriculture Investigations: - - F. L. Mulford. - W. Van Fleet. - -Bulb Culture Investigations: - - David Griffiths. - -Fruit and Vegetable Utilization Investigations: - - J. S. Caldwell. - C. A. Magoon. - C. W. Culpepper. - -Fruit Production Investigations: - - H. P. Gould. - L. B. Scott. - C. F. Kinman. - George M. Darrow. - E. D. Vosbury. - -Grape Production Investigations: - - George C. Husmann. - Charles Dearing. - F. L. Husmann. - Elmer Snyder. - G. L. Yerkes. - -Fruit Breeding and Systematic Investigations in Pomology: - - W. F. Wight. - Magdalene R. Newman. - -Fruit Improvement through Bud Selection: - - A. D. Shamel. - -Nut Investigations: - - C. A. Reed. - E. R. Lake. - -Fruit and Vegetable Storage Physiology: - - L. A. Hawkins. - R. C. Wright. - J. R. Magness. - J. F. Fernald. - -Extension Work (in cooperation with States Relations Service): - - W. R. Beattie. - C. P. Close. - - - - - UNITED STATES DEPARTMENT OF AGRICULTURE - - [Illustration] BULLETIN No. 816 [Illustration] - - Contribution from the Bureau of Plant Industry - - WM. A. TAYLOR, Chief - - Washington, D. C. [Illustration] January 19, 1920 - - - - - =STREET TREES.= - - - By F. L. Mulford, _Horticulturist, Office of Horticultural - and Pomological Investigations_. - - ----- - - CONTENTS - - Page - - Importance of Shade Trees 1 - - Public Control of Street Trees 6 - - Planning for Trees on City Streets 8 - - Spacing Trees 9 - - Conditions for Tree Growth 10 - - Kinds of Trees Suitable for City Streets 14 - - Qualities Necessary 14 - - Trees for Different Regions 16 - - Trees for Special Purposes 20 - - Descriptions of Street Trees 20 - - Culture of Street Trees 43 - - Selection of Individual Trees 43 - - Preparation of Holes 44 - - Planting 45 - - Pruning 50 - - Stakes and Guards 51 - - Later Care 52 - - Care of Mature Trees 53 - - Pruning 53 - - Feeding 55 - - Spraying 55 - - ----- - - - - -IMPORTANCE OF SHADE TREES. - - -The comfort to be derived from shade trees has long been recognized. The -early settlers of this country saved fine trees about their homes, on the -village greens, along the country roads, and in the fields. Later, as -villages grew, the householders planted trees adjoining their properties, -and the result has been the beautiful elm-shaded villages of New England, -the maple-shaded towns of New York and the Ohio Valley, and the oak-shaded -streets of the Southeastern States. (Fig. 1.) - -With time, the villages and towns became cities, and the woodlands were -largely destroyed. Conditions for tree growth were less favorable in the -cities, and nurseries had to be depended upon for planting material. With -these changed conditions the native trees of a region became less dominant -in the city planting and were largely replaced by those trees listed in -nursery catalogues which took the fancy of each property owner along the -street. (Fig. 2.) The quickest growing trees were considered first, and -as some of these made a big showing the first few years and were easily -transplanted, they have become the dominating trees in street planting -from the Atlantic to the Pacific and from the Great Lakes to the Gulf of -Mexico. (Figs. 2, 10, and 13.) A few have planted better and more lasting -trees (figs. 1, 3, and 4); but the tree growth on the streets of the -average town or city is ragged and unkempt in appearance, while that of -the suburb or small village is not much better unless the planting has -been done under municipal control and the plantings on a street have been -confined to a single kind of tree. - -[Illustration: P15311HP - -Fig. 1.--An oak-shaded street in the South. Willow oaks in Birmingham, -Ala., in late summer.] - -[Illustration: P18826HP - -Fig. 2.--A street with mixed plantings. The trees are of different -kinds, some unsuited for the purpose, planted at varying distances -apart, according to the inclination of the property holders. A street in -Stockton, Calif., photographed in early summer.] - -[Illustration: P12515HP - -Fig. 3.--American elms on a city street in midsummer. All these trees were -planted at one time at uniform distances apart by the Commissioners of -Washington, D. C.] - -The advent of such civilizing agencies as the telegraph, the telephone, -the electric light, and the trolley car have added each its share toward -the mutilation or destruction of the good trees that were in existence -at the time of their coming. Faulty methods of pruning also have caused -much disfigurement and ruin. (Figs. 5 and 21.) To this mutilation has been -added the unnecessary destruction of many trees in centers of business -(fig. 6), because they excluded a little daylight, or made a store -less prominent, or were somewhat in the way of using the sidewalk for -merchandise. - -In spite of all these troubles tree planting has continued because people -love trees, enjoy well-shaded streets, and are willing to make efforts to -get them. The trees on well-shaded streets are not only pleasing, but also -contribute toward the health of the community by transpiring moisture into -the atmosphere and by producing a restful effect on eyes and nerves. Red, -especially, is known to have an exciting effect on human beings, and where -city streets are well-shaded it makes less prominent those colors that -might otherwise prevail and offend. - -[Illustration: Fig. 4.--Trees 18 years old on adjacent streets: _A_, Pin -oaks; _B_, ginkgos; _C_, Norway maples. Note the differences in size.] - -Good shade is so appreciated that its presence adds a value to adjoining -properties. Real-estate men recognize this factor and plant shade trees -as early as practicable on land which they develop. That the beauty of a -city is improved by good street trees is becoming recognized more and more -and is finding expression in the desire of garden clubs, civic improvement -associations, and boards of trade for information on this subject. - -Success in planting street trees can be attained only by planning and -controlling the planting as a whole, by selecting the most suitable -varieties, by securing trees in the best condition and planting them -properly, and by giving the necessary later care. - -While towns were small, conditions for tree growth favorable, and -woodlands plenty, so that native trees were easily obtained and started, -the practice of each householder planting his own trees as he saw fit gave -good results. As towns became larger and impervious pavements took the -place of earth roads, the conditions for tree growth became more severe -and the results from the individual planting of trees less uniform. In -large cities the conditions to be met are so extreme that it has become -practically impossible for the average householder to grow street trees -successfully, or to do so only at excessive cost. Then, too, a lineman -in a few minutes often undoes what the individual has achieved with care -and years of patient waiting (see fig. 5). The trees and the lines are -both needed by the public, but when provided by individual initiative -at private expense, but trimmed for the benefit of electric lines by -employees of corporations intent on maintaining service at the least cost, -the trees suffer unduly. - -[Illustration: P16692HP - -Fig. 5.--A tree mutilated by linemen. An otherwise beautiful red oak in -Louisville, Ky., as it appeared in midsummer.] - -In order to have good shade trees at a reasonable cost which receive -timely and efficient attention, with the effective control of wire lines, -the care of the trees needs to be vested in some adequate authority. - - - - -PUBLIC CONTROL OF STREET TREES. - - -Providing shade on city streets is as much a municipal function as -providing lights or sidewalks and should, therefore, be cared for by -public officials. All street trees should be directly under the care of -duly appointed officers, who should be responsible for their planting -and care, as well as for their pruning or removal. Negative control by -requiring permits for planting, pruning, and removal is little better than -no control. - -[Illustration: P16986HP - -Fig. 6.--A desert of asphalt in the business center of a city having less -than 100,000 population.] - -The officials in charge should have the necessary authority and should be -required to initiate and carry forward planting and all other needed work -connected with the establishment and maintenance of street trees. Probably -the most satisfactory way of securing supervision is through an unpaid -commission of three or five members, which in turn employs an executive -officer. In a small place a commission of three persons may be best, one -being appointed every 2 years for a 6-year term. In large places five -members may be better, and the ideal term would be 10 years. A compromise -would be a 5-year term, a new member being appointed each year. The great -need of long-term appointees is that it takes two or three years for a -member of such a board or commission to see and realize the things needed -to be done and the policies that should be carried out. Because it takes a -long time to get results in growing street trees, the policies should be -as nearly continuous as possible and the terms of the members long enough -to insure a majority of experienced persons on the board at all times. - -The method of appointing the commissioners is not so important as that -each shall be selected from the territory as a whole rather than from a -part of it. In some places where the term of service is 10 years, each -one's successor is appointed by the remaining commissioners, subject to -confirmation by the court. Where this is done a member is not permitted to -succeed himself. In other places the commission is appointed by the court; -in others, it is elected by the city legislative body or is appointed by -the mayor subject to the approval of the legislative body. The important -point is to keep the administration as nearly as possible on a purely -business basis. - -A good board can accomplish nothing without liberal funds. There are two -methods of providing these: (1) By an appropriation from the general tax -levy and (2) by direct assessment against the properties, collectible -with the other taxes. If the funds are provided by appropriation, a -fixed minimum, expressed in millage of the tax rate, should be provided -in the organization of the commission. This minimum should be such that -a fair amount of maintenance work can be done when no other funds are -available. Councils that appropriate money sometimes hamper boards by -withholding appropriations. Work of the nature of tree planting should -not be permitted to suffer or be lost by a year's neglect. The fund -provided by this minimum amount should not be so large that regular -additional appropriations will not be needed to carry on the work -properly, as this will give a desirable point of contact of the commission -or board with the ordinary channels of expressing public sentiment in -the district interested. The minimum appropriation mandatory should be -sufficient to prevent injury from lack of care of work already begun. -A period of minimum care and attention while a board and the people or -their representatives are coming to a new understanding of one another's -position is not necessarily a detriment, provided a reasonable maintenance -has been possible in the interim, but without such care the results are -ruinous and work would better not be started than be undertaken with the -possibility of such a period of neglect occurring. - -It is probably desirable to assess the cost of tree planting against -the adjacent property owners at a proportional cost per front foot and -to provide for maintenance out of a general fund. Boulevards and other -unusual developments are sometimes maintained with satisfactory results by -regular assessments against the abutting properties. - -After a proper governing board is provided, the securing of a competent -executive is a matter of ordinary business procedure. It is usually -desirable that he shall be not only a good executive but also a man with -a knowledge of trees and trained in their care, so that he may be a -competent adviser of the board as well as its executive. - -[Illustration: P18857HP - -Fig. 7.--Increased attractiveness due to trees on a city street, as shown -by contrasting the two sides of the thoroughfare. If trees like red oaks, -American elms, or the Eucalyptus in the distance had been used, the effect -on this wide street would have been comparable to figure 3. The trees in -the left foreground are umbrella trees. Merced, Calif.; midsummer.] - - - - -PLANNING FOR TREES ON CITY STREETS. - - -With the help of one who knows trees and the local conditions to be -met, the town should be studied and a suitable kind of tree selected -for each street or for a large portion of a street (figs. 1 and 3), -and as conditions warrant the plan should be carried out as outlined. -Mixed plantings of different sorts of trees (figs. 2 and 7) are not as -pleasing and effective as the use of a single species for considerable -distances. The use of only one or two kinds for a whole town is likely to -be monotonous, and it is also undesirable because the variety most used -may become subject to serious disease or insect attacks. The species and -varieties of trees suitable for city planting are few enough, if all are -used, so an endeavor should be made to include as many different kinds as -practicable, assigning one variety for a long stretch of street unless -there is a marked change in its character, in which case a change of trees -would be warranted. - -Where trees are already on a street, the problem of planning for the -future is frequently much complicated, especially if there are several -kinds in good condition. Where there is but one good kind, gaps can be -replanted with young trees of that sort. If there are poor trees of a good -variety or trees of a poor or short-lived variety it would be advisable -to remove these and do all the replanting at one time, so as to have the -trees on the street as nearly uniform as possible. Where there are several -good varieties in good condition the sensible thing is to care for the -trees that are there and then, after careful study, decide on one variety -for all future plantings on that street. - -[Illustration: P14631HP - -Fig. 8.--Trees 20 feet apart that should be at least 60 feet apart. -Sycamores in Washington, D. C., as they appear in late winter.] - - - - -SPACING TREES. - - -A common fault in all street planting is to put the trees too near -together. (Fig. 8.) This is more evident where the work has been done by -the abutting property owners than by municipalities. - -After trees are started and have attained some size it is extremely -difficult to get them removed, even where the good of the remaining trees -demands it. The removal of a fairly good tree merely because it is short -lived in order to make room for a good one that will be permanent does not -appeal to the average citizen. Where trees which have been planted by the -property holder come under city control a strong feeling of proprietorship -still remains, which is outraged by the suggestion of the removal of even -poor trees. Where all the work is under city control good work is often -hampered by a strong public sentiment against the removal of trees, even -though they are poor or crowding. - -Because of this difficulty it is extremely important that young trees be -planted farther apart than at that time seems reasonable. If they are -planted as far apart as is proper for mature trees the distance will be -so great as to make planting seem a joke. If they are planted half the -distance apart they should be when mature, good results would follow if -the intermediate trees were removed when they nearly touch those to be -left. As the intermediate trees would probably not be removed, or not -until too late for the good of the remaining ones, planting had better -be sufficiently far apart in the beginning to avoid the necessity of -later removals. In the beginning the trees will be too far apart and when -mature too close together, but it seems to be the alternative imposed by a -misguided public opinion. - -There is scarcely a community that would permit the removal of -interplanted trees from a street of fine elms, oaks, or other worthy -varieties without a protest that would be the almost sure political -death of the administrative authorities responsible, no matter how great -the need or how much expert support they might have. If short-lived -intermediate trees were used they would not be likely to be taken out -before they died, and they probably would not die before they had -irreparably injured the permanent trees. The removal of surplus or -interplanted trees can be made with least shock to the community by -gradually narrowing the tree tops by severe pruning from year to year on -the sides next the permanent trees until finally they are so narrow they -may be removed and leave only small openings between the permanent trees. -Even this method will not materially lessen the public protest at the -final removal. - -A common practice is to set street trees 35 feet apart. If it were -practicable to remove one-half the trees at the proper time this would be -a good distance, but in the eastern half of the United States and on the -Pacific slope 50 feet apart is close enough for most varieties, and for -the larger growing trees 60 to 70 feet would be better. - - - - -CONDITIONS FOR TREE GROWTH. - - -In order to grow, trees must have a soil of suitable texture, in proper -mechanical condition, that contains sufficient available mineral elements -and plenty of organic matter, and, last but not least, a constant supply -of moisture and air. In addition to these there must be in active growth -in the soil many forms of organic life that are in various ways preparing -the material in the soil for the use of the larger plants. Not only must -these things be present, but others that are deleterious must be absent, -whether the substance is hurtful in itself or whether it is an excess of -one that is otherwise beneficial. - -Above the soil three things must be present--air, sunlight, and -moisture--and, as in the soil, harmful things must be absent in order to -have success. Among the deleterious substances are sulphur and other fumes -and soot and other products from incomplete combustion. - -[Illustration: P14633HP - -Fig. 9.--The irregularity in the size of the trees shown is due to a -part of the first planting having been killed by illuminating gas from -defective pipes. Norway maples as seen in Washington, D. C., in late -winter.] - -Some of the more obvious things with which a city tree has to contend are: -Water-tight pavements, both on the sidewalk and street, that prevent the -admission of air and water; the removal of the topsoil in street grading, -thus forcing the tree to exist on the good soil provided in the hole; -careless digging near the tree for gas, water, and electric service, and -especially for the placing of curb-stones; the saturation of the soil with -illuminating or sewer gas from defective pipes (fig. 9); the pouring of -salt water from ice-cream freezers into gutters, where it may find its way -into the soil near tree roots; the gnawing of the trunks by horses; and -the cutting of the tops by linemen and tree trimmers. - -Because of the uncongenial conditions for the growth of trees on city -streets comparatively few kinds are satisfactory for such use. Among -those available are some that will grow under extremely trying conditions. -Kinds can be found that will thrive wherever it is suitable for human -beings to live. If it is impossible to grow trees on a street, as a health -measure that street should be closed for human use until conditions are so -improved that it will support trees. - -[Illustration: P15298HP - -Fig. 10.--A business center relieved by a parking with Carolina poplars. -Macon, Ga.; late summer.] - -More kinds will thrive under suburban conditions where only a small -portion of the roadway is covered by an impervious coating, where the -parking spaces are liberal, and where the street is lined with open lawns -than under the conditions in a city, where the street is covered with a -water and air proof coating and the sidewalks with an impervious material, -where parking spaces are limited, and where adjoining lawn areas are small -or lacking. By a careful selection of kinds, all conditions in a city can -be met. In some places bad conditions could have been improved greatly by -a little forethought; in others, such conditions can be bettered. These -details, like many other matters connected with city planning, have been -ignored, but should be considered immediately, especially by villages and -small cities. Figure 6 shows how an opportunity for creating a beauty spot -has been lost sight of, while figure 10 shows how a city has utilized less -ground to increase the comfort and attractiveness of its business center. - -[Illustration: P15278HP - -Fig. 11.--A street well proportioned in width of roadway, sidewalk, and -parkings, with willow oaks on the left, American elms on the right, and -young Carolina poplars near the roadway that should be removed. Columbus, -Ga.; midsummer.] - -[Illustration: P14359HP - -Fig. 12.--A street with too much pavement and too little parking space. -Carolina poplars in Baltimore, Md., in midautumn.] - -A common mistake in ambitious young cities and many old ones is to pave -more of the width of the street for traffic purposes than, is likely ever -to be needed. By reducing the roadway and throwing the remainder into -liberal parking spaces much is added to the attractiveness and comfort -of a city. A contrast in the two methods of treatment is illustrated -in figures 11 and 12. The recommendation that the roadway prepared for -travel be made narrow is not to be interpreted as a reason for lessening -the area dedicated to the public use; in fact, in most cities, especially -in the northeastern quarter of the United States, too little space has -been reserved from houseline to houseline (fig. 13). By reserving more -room between the houses and the street for use as lawns and gardens the -conditions would be made more livable, opportunity would be offered for -widening the public way without prohibitive expense if traffic or business -demanded it, and the growing of street trees would cease to be a serious -problem. - -[Illustration: P16842HP - -Fig. 13.--A street with too little room from houseline to houseline. Note -the more attractive appearance of the side with trees. Norway and silver -maples in Frederick, Md., in midsummer.] - - - - -KINDS OF TREES SUITABLE FOR CITY STREETS. - - -QUALITIES NECESSARY. - -Compared with the whole number of trees used for ornamental planting, the -number of kinds suitable for street planting is very small. For use under -city conditions a tree must be adapted to the climate and to the soil upon -which it is to be grown. It must have healthy foliage that withstands -dust and smoke and a root system not easily affected by unusual soil -conditions, by restricted feeding areas, or by root pruning when street -improvements are made. The top should be in proportion to the width of -the street upon which it is used, and it should be rather high headed or -easily trained to that form and of open growth without being too spreading -or sprawling. - -Of minor consideration is the character of the foliage masses, whether -dark or light, heavy and somber or open and airy, and also whether they -have vivid autumn colorings. Only in the most southern parts of the -country and in western California should evergreen trees be considered -for street planting, and then only the broad-leaved evergreens, such as -magnolias and live oaks. In the North the lack of sunshine during the -short cloudy days of winter makes it desirable to admit all the light -possible. Even in the South the question of sunshine should be considered -when selecting varieties. - -[Illustration: P12536HP - -Fig. 14.--Narrow upright trees (Lombardy poplars) on a Barrow Conditions, -it is better street. Washington, D. C.; midsummer.] - -Narrow streets should be planted with columnar trees (fig. 14) or -sometimes with small trees. Broad streets may be planted with spreading -trees (figs. 3 and 16), or, if provided with a central parking space, with -moderate-sized trees in the center and on the sides, or with trees on the -sides suited to the space and formal trees in the center. (Fig. 15.) - -[Illustration: P18856HP - -Fig. 15.--Formal trees in a central parking, but appropriate trees wanting -on the sides of the street. Canary Island date palms in Merced, Calif.; -midsummer.] - -As a rule, trees native to the locality that have been successfully grown -in other cities should be given the preference. When a choice must be made -between untried native trees and those tested in a city or town under -different soil or climatic to give the native trees the first trial. There -are many native trees that are promising which have not been planted on a -sufficient scale or under sufficiently varied conditions to demonstrate -their real value for street planting over any considerable area. Many of -the trees mentioned in this bulletin may prove valuable far beyond the -areas for which they are suggested. The burr oak, the swamp white oak, the -scarlet oak, the chestnut oak, the white oak, the sour gum, and others may -be found on further trial to be as valuable as those already demonstrated -to be valuable over large areas. Those mentioned have all been tested in a -small way. - -Caution should be used in selecting trees with conspicuous flowers and -those with edible fruits or nuts, as in many parts of the country such -trees are badly mutilated by the public. Even horse-chestnuts, although -the nuts are not edible, are often broken by boys clubbing the trees. -That public opinion can prevent such vandalism is in evidence all along -the Pacific coast and at a few places in the East. Every effort should be -made to create a sentiment that will protect these attractive additions to -street adornment, but where the sentiment does not exist it is better to -avoid the planting of such trees except in a limited way. - -[Illustration: P15394HP - -Fig. 16.--Live oaks, the handsomest southern street tree for broad street: -Biloxi, Miss.; late summer.] - -Besides the native trees there are many introduced trees that have proved -valuable and many more that are worthy of trial.[1] A fair trial of -promising introduced trees should be made, and the native kinds should be -thoroughly tested. - -[1] As examples of this are a number of new elms such as _Ulmus -pumila_ and _Ulmus densa_, besides lindens, poplars, and _Koelreuteria -paniculata_, while _Pistacia chinensis_ is suitable for warm regions. -The Office of Foreign Seed and Plant Introduction of the United States -Department of Agriculture will be glad at any time to suggest new trees -that are promising for any region. - - -TREES FOR DIFFERENT REGIONS. - -To simplify the discussion of kinds of street trees likely to prove -satisfactory, the United States has been arbitrarily divided into the -regions shown in figure 17. An endeavor has been made to make each -division cover an area having similar growing conditions, so that the -trees suggested will be likely to thrive in all its parts. A discussion -of the strong and weak points of the different kinds will be found with -the description of the kinds farther on in this bulletin. - - _Region 1._--Region 1 comprises the mild humid portion of the northern - Pacific coast east to the Cascade Mountains, including the western - third of Washington and Oregon and a portion of northern California. - The trees native to western Europe are adapted to this region, as the - climatic conditions are quite comparable. Most of our American trees - also succeed here. - - Some of the desirable varieties for street planting in region 1 are - the Oregon, Norway, sycamore, and sugar maples; California walnut; - tulip; European linden; basswood; sycamore; London plane; white and - European ashes; English and American elms; English, red, and pin oaks; - ginkgo; and the black locust. - -[Illustration: Fig. 17.--Outline map of the United States, showing the -regions within which essentially similar conditions for tree growth exist.] - - _Region 2._--Region 2 is that portion of California lying between - the Sacramento and San Joaquin Valleys and the Pacific Ocean. Many - varieties of trees will succeed here if given water. Because of the - lack of water, unless specially irrigated the more drought-resistant - species should be used. - - Among the deciduous trees useful for this region are the London plane; - the California and common sycamore; English, Huntingdon, and American - elms; Oregon, Norway, sycamore, and English maples; white, green, and - European ashes; red, English, and pin oaks; European linden; basswood; - California walnut; honey and black locusts; horse-chestnut; Albizzia; - and the Japanese varnish tree, or Sterculia. - - Evergreen trees which will probably be successful in region 2 are the - Eucalyptus[2] in variety, acacias, rubber, magnolia, California live - oak, Victorian and poplar-leaved bottle trees, and in the southern - portions the California pepper, silk oak, and jacaranda. Palms are - much planted, but they do not make good street trees except where a - formal effect instead of shade is desired. - -[2] Some cities have ordinances against the planting of certain trees -because their roots sometimes obstruct sewers. Among these trees are the -Eucalyptus in California and some of the poplars in several of the States. - - - _Region 3._--Region 3 comprises the Sacramento and San Joaquin Valleys. - - The deciduous trees for this region are the California walnut; London - plane; California and common sycamores; Oregon, Norway, and sycamore - maples; white, European, and green ashes; red, English, valley, and - pin oaks; European linden; basswood; English and Huntingdon elms; - honey locust; and horse-chestnut. Chinaberries and Texas umbrellas are - much planted in these valleys, but are not good street trees. Olives - and palms are suitable only for formal effects, while eucalypti are - satisfactory but are liable to make trouble with defective sewers. - Acacias grow especially well in this region except in the extreme - north. - - _Region 4._--Region 4 includes the country from the Sacramento and San - Joaquin Valleys to the crest of the Sierra Nevada Mountains. It varies - in elevation and correspondingly in temperature and the amount of - available moisture. - - Where there is sufficient moisture, the deciduous trees recommended - for region 3, except the valley oak and possibly the California - sycamore, may be used. Where there is less moisture the thornless - honey locust, black locust, green ash, hackberry, poplars, ash-leaved - maple, and the American elm if it can be watered the first few years - may be planted. In the warmer sections the chinaberry and Texas - umbrella may be used. - - _Region 5._--Region 5 comprises the hot semiarid country of southern - California and southwestern Arizona which is dependent on irrigation. - - The best deciduous trees for this region are those suggested for the - drier portions of region 4. With ample irrigation the deciduous trees - recommended for region 3 might grow. - - Among the evergreens the Texas palmetto, Parkinsonia, and the - Washingtonia and some other palms can be used where other trees do - not succeed. The red and desert gums may be used also in the drier - regions. With ample irrigation the evergreens suggested for region 2 - should succeed. - - _Region 6._--Region 6 comprises the intermountain section and extends - from the crest of the Cascade and Sierra Nevada Mountains eastward to - the eastern base of the Rocky Mountains. The region includes great - variations in growing conditions, often in very short distances. As a - whole it is semiarid, and in most places trees can hardly be expected - to thrive without more or less irrigation, although in some of the - mountain valleys and on some of the mountain slopes almost ideal - conditions for tree growth exist. - - In the drier parts of the region only those deciduous trees that are - weeds under more congenial conditions can be grown. Those that can - be planted with the greatest hope of success are the thornless honey - locust, black locust, green ash, hackberry, and where the others do - not succeed, the poplars and ash-leaved maple. If it can be watered - for a few years the American elm usually can be grown, and in the - southern half of the region the Mississippi hackberry will probably - succeed. Near the southern border, on lower elevations, the chinaberry - and Texas umbrella can also be planted. In the locations most favored - naturally or where irrigation is possible, the trees suggested for - region 9 can be used. - - Evergreens that may be used for the drier portions of the southern - part of region 6 are the Parkinsonia and the Texas palmetto. - - Native trees may be found that will prove of greater value for limited - areas than any suggested. Cities and towns contemplating street tree - planting would do well to consult the nearest State agricultural - experiment station or the United States Department of Agriculture if - it is thought possible that something better has been found than the - trees suggested. - - _Region 7._--Region 7 is the northern part of the Great Plains area - from the foot of the Rocky Mountains at about the 5,000-foot contour - line east to the ninety-eighth meridian. It is rather uniform in - general conditions, the character of soil having no wide divergence - and the elevation increasing gradually from south to north and east - to west. The rainfall gradually increases from west to east until at - about the ninety-eighth meridian the conditions are more favorable for - tree growth. - - The trees to be relied on are the thornless honey locust, common - hackberry, black locust, green ash, ash-leaved maple, the poplars, - the Chinese elm, and the American elm if it can be watered the first - few years after transplanting. The mossy-cup oak is another tree - worth testing in a small way, as it is native a little east of the - ninety-eighth meridian. The basswood and Norway maple would probably - succeed if supplied with plenty of water. - - _Region 8._--Region 8 is the southern part of the Great Plains. - - In addition to the deciduous trees recommended for the northern Great - Plains (region 7) the Mississippi hackberry, Texas umbrella, and - chinaberry may be successfully grown. - - Evergreen trees that may be used in region 8 are the Texas palmetto - and Parkinsonia. - - _Region 9._--Region 9 is the upper Mississippi Valley, including - the area from that already considered to Lake Michigan and south to - southern Kansas. It is more favorable to tree growth than regions 6 - and 7. - - Trees which will succeed here are the American elm; red, pin, - mossy-cup, and other native oaks; white ash; sycamore; basswood; and - Norway and sugar maples. - - _Region 10._--Region 10 includes the northeastern part of the country - from eastern Illinois to the Atlantic Ocean, and extends southward - through the Appalachian Mountains. It is most favorable for tree - growth. - - The best trees for street planting in region 10 are the red and pin - oaks, London plane, sycamore, the staminate form of the ginkgo, - basswood, tulip, Norway maple, white ash, thornless honey locust, - American elm, and in the southern portion of the region on light land - the sweet gum. The red and sugar maples are among the best trees for - suburban conditions. The hackberry will grow, but should be discarded - in favor of better varieties. The mossy-cup and chestnut oaks are - worthy of trial on gravelly soils in the suburbs. - - _Region 11._--Region 11 includes the lower Mississippi Valley and the - country east of the southern Appalachian Mountains, extending from the - light lands near the South Atlantic and Gulf coasts to the northern - limits of the distinctively southern flora. - - The typical street trees of this region are the willow oaks (fig. 1) - and water oaks, the former a valuable street tree, the latter good - when young but comparatively short lived, with no advantages over the - willow oak. Other good trees are the red, Spanish, laurel, Darlington, - and pin oaks, tulip, sweet gum, American elm, red and Norway maples, - and the ginkgo. - - _Region 12._--Region 12 is the land near the coast from Wilmington, N. - C., to the Mexican border, exclusive of the southern part of Florida. - - Good deciduous trees for this region are the willow, laurel, - Darlington, and Spanish oaks, tulip, sweet gum, sycamore, London - plane, American elm, and the staminate form of the ginkgo. The honey - locust, red or scarlet maple, Norway maple, and the hackberries are - not so good. - - The live oak is the characteristic tree of region 12 (fig. 16) and is - the pride of the cities that have used it. Even though an evergreen, - it is an excellent street tree, as it is large, spreading, and open. - The palmetto and palms thrive and may be used for producing formal - effects. The evergreen magnolia is a good broad-leaved evergreen. - - _Region 13._--Region 13 consists of the southern part of Florida. The - deciduous trees suitable for this section are the willow, Spanish, and - southern red oaks; American elm; Mississippi hackberry; and in the - southern half of the region the Poinciana. - - Evergreen trees are better suited to region 13 than to, any other - portion of the United States except possibly southern California. - Among the best are the live and laurel oaks, evergreen magnolia, - camphor, rubber, silk oak, or grevillea, and casuarina. Eucalypti are - planted to some extent in Florida, but the climate is such that only - on the drier grounds of the interior are they likely to succeed, and - even there they are not to be compared with other excellent species of - trees that may be cultivated successfully. - - -TREES FOR SPECIAL PURPOSES. - -In the heart of a city, where the greatest difficulty is experienced in -getting trees to grow, the ailanthus will probably thrive when nearly all -other kinds fail. The sycamore and the London plane are also good for such -places. The Carolina poplar will frequently grow under these conditions, -and its use may sometimes be warranted. - -For very narrow streets the Lombardy poplar is the best tree. (Fig. 14.) -Trees suitable for use within the reach of ocean spray or on sandy lands -near the coast are the red oak and the red or scarlet maple south to -Charleston, S. C., while the sweet gum and the live oak are equally good -from Norfolk southward and along the Gulf of Mexico. The red oak, sweet -gum, red maple, and eastern live oak are all grown successfully along -the Pacific Ocean, while the California live oak can be used from San -Francisco southward. The trees that endure the most alkali appear to be -the bladder-nut tree,[3] London plane, peppermint gum,[4] blue gum,[5] -the Washingtonia and other hardy fan palms, Canary Island date palm, the -camphor tree, and _Acacia cyclops_ and _Acacia retinodes_. Only the first -two withstand severe freezing weather. The red oak and the red maple are -worth testing for these conditions. - -[3] _Koelreuteria paniculata_. - -[4] _Eucalyptus amygdalina_ Labill. - -[5] _Eucalyptus amygdalina angustifolia_. - - - - -DESCRIPTIONS OF STREET TREES. - - -ACACIA. - -The acacias, or wattles, are a large group mostly of small trees with -showy yellow flowers. Although much used in California, many of them are -too small to make satisfactory shade trees, and because of shallow rooting -they are injurious to sidewalks. They also stump-sprout badly. They thrive -in regions 2 and 3 and in restricted portions of regions 1 and 5. - -The Australian blackwood,[6] blackwood acacia, or wattle, is a strong, -upright tree, growing to a height of 75 feet and forming a well-shaped -head. It is badly affected by citrus scale, and on this account its -planting is sometimes prohibited. - -[6] _Acacia melanoxylon_ R. Br. - -The black wattle[7] is a strong-growing round-headed tree that reaches a -height of 40 feet and has dark-green leaves. - -[7] _Acacia decurrens mollis_ Lindl. - -The green wattle[8] is a rapid-growing tree, reaching a height of 60 feet -and forming a round head with finely cut leaves. - -[8] _Acacia decurrens_ Willd. - -The silver wattle[9] is much like the black wattle except that its leaves -and young branches are covered with a whitish down. - -[9] _Acacia decurrens dealbata_ F. Muell. - - -AILANTHUS. - -The ailanthus,[10] or tree of heaven, is a tall, broad, handsome tree that -is especially valuable in the heart of closely built or smoky cities. -The staminate and pistillate flowers are borne on separate trees. Only -the pistillate trees should be used, as the odor of the blossoms of the -staminate ones is very objectionable for about 10 days in late spring. -These may be produced by grafting from pistillate trees or by propagating -from suckers or root cuttings from such trees if they have not been -grafted. The ailanthus may not succeed in regions 5 and 13. - -[10] _Ailanthus altissima_ (Mill.) Swingle (_A. glandulosa_ Desf.). - - -ASH. - -There are three kinds of ash trees that are useful for street planting. - -The white ash[11] is a large oval-headed tree, reasonably satisfactory -on rich lands in regions 1, 2, 3, 4, 9, 10, 11, and 12, but it is better -adapted to suburban than urban conditions. - -[11] _Fraxinus americana_ L. - -The green ash[12] is one of the few successful trees in regions 6, 7, and -8 and may succeed in region 5. It grows well throughout the remainder of -the United States, but is of less value than other trees there. It is much -smaller than the white ash, with a broad round top. - -[12] _Fraxinus lanceolata_ Borck. - -The European ash[13] is a large, handsome, round-headed tree suited to -regions 1, 2, 3, and 4. - -[13] _Fraxinus excelsior_ L. - - -CAMPHOR. - -The camphor tree[14] is a large, handsome, oval-headed evergreen that will -succeed in the southern half of region 2, in regions 3, 5, and 13, and in -the warmer parts of region 12. It will endure more frost than the orange, -and where it is successfully grown it is deservedly popular. - -[14] _Cinnamomum camphora_ (L.) Nees and Eberm. - - -CHINABERRY. - -The chinaberry,[15] sometimes known as the China tree, is a small, -round-headed, short-lived tree that will grow in regions 2, 3, 5, 8, 11, -12, and 13 and near the southern edge of region 6. It is too short lived -to be considered for planting where other trees will grow. - -[15] _Melia azedarach_ L . - -The umbrella tree,[16] or Texas umbrella, is a small, compact form of the -chinaberry with an umbrella-shaped top. It is useful for formal effects, -as in the parking on a wide street where taller trees are used on the -side. It will grow in regions 2, 3, 5, 8, 11, 12, and 13 and in the -southern parts of region 6. - -[16] _Melia azedarach umbraculiformis_ Berckmans and Bailey. - - -ELM. - -The elms are large, handsome shade trees suitable for use over a wide -range of territory. - -[Illustration: P12460HP - -Fig. 18.--An American elm with crotches liable to be split by heavy winds. -Note the supporting chains.] - -The American elm[17] sometimes called the white elm and water elm, is -one of the handsomest American shade trees. (Fig. 3.) It has been the -standard street tree of New England, giving to the roadsides and village -streets the characteristic appearance which is so attractive to summer -visitors. - -[17] _Ulmus americana_ - -The American elm is tall and spreading, and where planted as near together -as is customary on streets and country roads the effect of the mature -trees is that of an arch formed by the growing together of their spreading -tops. It is of rapid growth and long lived. - -This elm drops its leaves very early in the fall, but it comes into leaf -early in the spring. Because of its manner of branching it is especially -liable to be split by heavy winds. This trouble may be lessened by -selecting and planting specimens with a close, compact habit of growth or -possibly also by great care in training young trees. Two limbs separating -from one another by a very small angle, that is, when they start to grow -in nearly the same direction, make a crotch that is liable to split. (Fig. -18.) Where two limbs separate at nearly a right angle or where three or -more limbs of about equal size grow from a common point or very nearly so, -the crotch is likely to be much stronger. Careful pruning and training to -provide a proper system of branches may be especially helpful with this -elm. - -Because of the attacks of the elm leaf-beetle[18] and the European elm -bark louse,[19] many handsome trees have been severely damaged or killed -before communities were properly equipped for fighting them, for with -careful spraying these insects may be kept in check. However, on account -of the existence of these pests and because they are gradually spreading -to new territory, tree planters should consider carefully whether it -is advisable to plant the elm in their localities. Where there is no -danger from these insects, this elm is one of the best of street trees. -Consultation with the nearest State agricultural experiment station or -with the Entomologist of the United States Department of Agriculture would -be advisable in order to determine this point. - -[18] _Galcrucella luteola_ Mull. - -[19] _Gossyparia spuria_ Mod. (Data regarding both insects furnished by -the Bureau of Entomology.) - -The best specimens are to be found in the northern part of region 10, -although the elm is being grown all over the United States and is proving -a valuable street tree even in towns and villages of regions where the -rainfall is as low as 15 inches. It is not recommended for planting in -regions 3 and 5. - -The English elm[20] is a tall, oval-headed, compact, handsome tree with -leaves smaller than the American elm and which stay on much later in the -fall. In regions 1 and 2 it is at its best, in the former equaling the -American elm and in the latter excelling it. It also thrives in regions 3 -and 10 and in the eastern part of region 11. - -[20] _Ulmus campestris_ L. - -The Huntingdon elm[21] is a comparatively round-headed European variety. - -[21] _Ulmus hollandica vegeta_ (Lindl.) Rend. - -It is a large, handsome tree with good foliage and is more compact in -growth than the American elm. It succeeds well in regions 1, 2, 3, and 4. - -The wahoo, or winged elm,[22] is native to the South Atlantic and Gulf -States near the ocean. It has larger leaves than the American elm and is -not as spreading in its growth, but it succeeds well on city streets in -regions 11, 12, and 13. - -[22] _Ulmus alata_ Michx. - - -EUCALYPTUS. - -There are a large number of species of Eucalyptus, many of which can be -used for street planting in regions 2, 3, and 5. Some cities prohibit -their planting because their roots are liable to penetrate defective -sewers, and in other cities they must be kept at least 70 feet from a -sewer, though even this distance may not prove permanently effective. - -The roots of any tree are liable to find their way into a defective -sewer, but the trees mentioned are especially noticeable because of their -vigorous root growth. It may be questioned whether a tree should be -condemned for this growth, as it may be better to have a defective sewer -thus revealed than to continue a menace to public health. - -Eucalypti are also being planted in southern Florida, but on account of -the moist climate there it is not to be expected that they will succeed -as well as in the other regions mentioned. They are tall, handsome, -quick-growing trees, usually bearing two kinds of leaves at some time in -their development. - -The blue gum[23] is one of the best eucalypti and the one most commonly -used in California. It is tall, globular headed, handsome, and will -survive several degrees of frost, but it will not withstand the heat of -the deserts in region 5. Its roots are especially liable to invade sewers. - -[23] _Eucalyptus globulus_ Labill. - -The desert gum[24] is one of the trees most resistant to heat and cold, -and it makes a handsome avenue tree. It has pendent branches that have a -tendency to severe splitting with age, but with early attention this may -be overcome largely. It may prove especially valuable for region 5. - -[24] _Eucalyptus rudis_ Endl. - -The manna gum[25] is another Eucalyptus which withstands several degrees -of frost and makes an excellent roadside tree. Some forms shed their bark -in long bands that leave the trunks almost white. Many people consider it -a dirty tree on this account. - -[25] _Eucalyptus viminalis_ Labill. - -The red gum[26] grows with a broad head, is one of the most resistant of -the eucalypti to frost, drought, and heat, and succeeds wherever any of -these trees can be grown in regions 2, 3, or 5, but is most useful in -region 5. - -[26] _Eucalyptus longirostris_ F. Muell. - -The sugar gum[27] is a drought-resistant variety, but it does not -withstand cold. It is a common roadside tree in southern California, but -becomes straggling with age. - -[27] _Eucalyptus corynocalyx_ F. Muell. - - -GINKGO. - -The ginkgo,[28] or maidenhair tree (fig. 4, _B_), is a native of Japan -that thrives in a cool climate or a hot, moist one and succeeds in regions -1, 9, 10, 11, 12, and 13. It is extremely erratic in its behavior, -sometimes growing well, sometimes practically not growing at all, but -where it succeeds it is very disease resistant, and it withstands severe -windstorms remarkably well. The leaf is peculiar in appearance, resembling -in outline a much enlarged leaflet of maidenhair fern with a corrugated -surface. The tree is conical when young, but as it reaches maturity its -top usually fills out, making a broad, almost flat-topped, handsome tree. -Only the staminate form should be used, because the pistillate form bears -fruits the flesh of which is slippery and dangerous when it drops to the -pavement, and to some people it is somewhat poisonous to the touch. Ginkgo -trees, therefore, would need to be secured by budding or grafting from the -mature staminate form. - -[28] _Ginkgo biloba_ L. - - -HACKBERRIES. - -The hackberry,[29] or sugarberry, is especially valuable in regions 6, 7, -8, and 9, as it grows satisfactorily where there is comparatively slight -rainfall. It is also much used in region 11, but should be superseded -there by other varieties that are better. It is of moderate size with an -oblong head and of rather open growth. It is comparatively short lived. -Its leaves are much like those of the elm. - -[29] _Celtis occidentalis_ L. - -The name sugarberry comes from the sweet black berries that are borne -in the early fall. The tree is sometimes affected by a fungous trouble -known as witches'-broom. This trouble causes large numbers of small -sprouts to start from the affected portion, which gives the infected tree -an unsightly appearance. The hackberry should not be planted where this -trouble is prevalent. - -The Mississippi hackberry[30] is a large, open, oblong-headed tree with -smoother leaves than the common hackberry. It is useful in the southern -part of region 6, in region 8, and to some extent in regions 11 and -12. It thrives well under the same adverse moisture conditions as the -common hackberry. The trunk and the large branches have little wartlike -projections of the bark scattered irregularly over them. The small twigs -are sometimes more or less spotted or winged in the same way. The tree is -rather larger than the common hackberry and apparently is less subject to -witches'-broom. - -[30] _Celtis mississippiensis_ Bosc. - - -HONEY LOCUST. - -The honey locust[31] is a large, open, round-headed, fine-foliaged tree, -admitting much light through its top. (Fig. 19.) The common form has stiff -spines 2 to 6 inches long, or even longer. There is also a form without -spines, which is the one that should be used for street planting. It is a -useful tree in regions 1, 2, 3, 9, 10, and 11, but is especially valuable -for planting in regions 6, 7, and 8, and may prove useful in region 5. - -[31] _Gleditsia triacanthos_ L. - -[Illustration: Fig. 19.--A street shaded with honey locusts, as seen in -late summer. Washington, D. C.] - - -HORSE-CHESTNUT. - -The horse-chestnut[32] has handsome blossoms that are very showy, and -when in bloom an avenue of these trees commands attention. It is a close -relative of the buckeye, or Ohio buckeye, which is also a handsome tree, -though less desirable. It is objectionable because it is likely to be -broken by boys clubbing it for its nuts, which are inedible, or where -its leaves are affected with a midsummer blight which makes it unsightly -during the remainder of the season. It is a medium-sized round-headed -tree that does much better under suburban than under city conditions. It -thrives in regions 1, 2, 3, and 10. - -[32] _Aesculus hippocastanum_ L. - - -LINDEN. - -The basswood,[33] or linden, is a large round-headed tree that is -excellent for roadsides in suburban locations and does well on city -streets if the conditions are not too severe. On account of the dark upper -surface and the lighter under surface of the leaves and the sweet-scented -blossoms in early summer it is much admired. It is not as reliable as -some of the other shade trees, as when young it is sometimes attacked at -the base of the trunk by a fungous growth that kills the tree. When once -established it forms handsome avenues. It is suited to regions 1, 2, 3, 4, -7, 9, 10, and 11. - -[33] _Tilia americana_ L. - -The linden,[34] or European linden, has much smaller leaves than the -American linden, or basswood, with more contrast between their upper and -lower surfaces. It is not much different in size, but is a little more -compact in growth and holds its leaves longer in the fall. It is a useful -tree for street planting in regions 1, 2, 3, 4, 9, 10, and 11. - -[34] _Tilia platyphyllos_ Scop. - - -LOCUST. - -The locust,[35] or black locust, is one of the desirable street trees -in regions 6, 7, 8, and probably in region 5, as it thrives with -comparatively little moisture. It makes a moderate-sized oval head that -bears sweet-scented white flowers in late spring or early summer. Its -greatest drawback is its liability to serious injury and disfigurement -by the locust borer,[36] but with proper care this injury can be -prevented.[37] In some parts of the East it is also subject to a leaf -miner[38] that gives its foliage a burned appearance. In region 3 it holds -its seed pods for several years and thus becomes very unsightly. - -[35] _Robinia pseudacacia_ L. - -[36] _Cylene robiniae_ Forst. (Data furnished by the Bureau of Entomology). - -[37] See U. S. Dept. of Agriculture Bulletin 787, entitled "Protection -from the Locust Borer." - -[38] _Chalepis dorsalis_ Thunb. - - -MAGNOLIA. - -The evergreen magnolia[39] is one of the few good evergreen trees for -street planting, but it is adapted only to regions 1, 2, 3, 11, 12, and -13. There are but few conditions that warrant the planting of a tree -having foliage as thick as this, because of the dense shade, which is -especially undesirable in winter. It grows to be a large oval-headed tree -and bears beautiful large white blossoms in late spring or early summer. - -[39] _Magnolia grandifolia_ L. - - -MAPLE. - -Among the maples are some undesirable trees much used for street planting -and some that are valuable only in restricted areas or under special -conditions. The maples are not as satisfactory for street planting as -usually has been supposed, few of the species being suitable for this -purpose and these only in a limited way. The ash-leaved maple, or box -elder,[40] is native to all of the country east of the Rocky Mountains -except the regions near the South Atlantic and Gulf coasts. It is a small, -quick-growing tree that will thrive almost anywhere, but it reaches -maturity early. Because of its early decay and of its being subject to -destruction by wind, it should not be used for street planting where other -trees succeed. It would be a good tree for interplanting were it safe -to risk taking out some of the trees at the right time. The objection -to using these trees is that they would be so likely to look larger -and better than the permanent trees at the time they should be removed -that public opinion would probably resent their removal. There may be -conditions requiring the use of this tree in regions 6, 7, and 8, but it -should be grown only when the other trees suggested for these regions will -not succeed. - -[40] _Acer negundo_ L. - -The English maple[41] is small, round-headed, with small dark-green -leaves, useful in regions 1, 2, 3, and 4. - -[41] _Acer campestre_ L. - -[Illustration: P20042HP - -Fig. 20.--A Norway maple, as seen in late winter, showing its poor shape -when trimmed to a high head.] - -The Norway maple[42] is round-headed and eventually reaches large size, -but, as compared with most of the other maples, it is slow growing (fig. -4, _C_). The persistence of its tendency to form a low head makes it -difficult to give it a high head of desirable shape (fig. 20). It is -also very thickly branched, and its foliage, being heavy and dark-green, -permits but little light to pass through. On this account it is rather -undesirable for street planting. By severe pruning of the interior of -the head this defect may be somewhat overcome. The tree is practically -disease and insect free, with the exception of a liability to infestation -by a leaf aphis[43] which produces yellow spots on the leaves and causes -them to drop prematurely; also, the honeydew which they produce is so -abundant at times as to cover the leaves and wet the sidewalk beneath the -tree, the leaves under certain weather conditions becoming blackened with -dust accumulating and a fungus growing in the secretion, thereby giving -the tree an unsightly appearance. This aphis, however, is not always -present and does not seriously injure the tree. The Norway maple comes -into leaf later than most of the other maples, but holds its leaves later -in the fall. They usually assume a bright yellow hue before they drop. The -leaves are preceded by an abundance of yellow-green blossoms. On account -of its dense shade and masses of fine fibrous roots it is difficult to -grow grass under this tree. Its good shape and attractive dark-green -foliage make it popular for street planting in spite of its dense, low -head. It will succeed in regions 1, 2, 3, 4, 9, 10, 11, and 12. - -[42] _Acer platanoides_ L. - -[43] _Periphyllus lyropictus_ Kess. (Data furnished by the Bureau of -Entomology.) - -The Oregon maple[44] is the large-leaved maple of the northern Pacific -slope. It forms a large round head, and with its unusually large -dark-green leaves makes a very attractive street tree that succeeds well -in regions 1, 2, 3, and 4. It is valuable and worthy of more extended -cultivation on the Pacific coast. - -[44] _Acer macrophyllum_ Pursh. - -The red maple,[45] scarlet maple, or swamp maple is one of the most widely -distributed of American trees. It is found from Canada to the Gulf of -Mexico and west to the Rocky Mountains. Its leaves are the smallest of any -of the eastern native maples, but it grows large and the trees are usually -of rather upright outline. It is better adapted to suburban conditions -than to city streets and is one of the few trees that succeed well near -the ocean. It has bright-red blossoms before the leaves appear. The young -leaves and fruits are also red. The mature leaves begin to color early, -some branches coloring as early as the middle of July, assuming brilliant -reds and yellows and staying on later than those of the sugar maple. It is -a handsome tree that is not as much used as it deserves to be in regions -1, 9, 10, 11, 12, and 13. - -[45] _Acer rubrum_ L. - -[Illustration: P12542HP - -Fig. 21.--Silver maples severely headed back, an improper way to treat -trees, especially silver maples, except under very unusual conditions. -Washington, D. C.; midsummer.] - -The silver maple,[46] also called the soft maple, white maple, and swamp -maple, is probably more used for street planting through the whole -United States than any other tree, and with one exception it is the -least desirable. It is usually planted because it is a quick-growing -tree, but it is not more rapid in growth than several other much better -trees. There are three serious objections to its use as a street tree. -The first is its brittle wood, which at an early age is easily broken -by ordinary windstorms and causes it when a comparatively young tree to -become unsightly. The second is its shallow rooting, which has a tendency -to destroy pavements and also makes it difficult to grow grass near the -trees. The roots also will grow into sewers. The third is the tendency to -decay; the tips of the limbs frequently die, leaving the whole top of the -tree bare of leaves, and the wood decays quickly, especially if the bark -is broken. For this reason it does not stand pruning as well as most other -street trees, and it probably has been pruned more ruthlessly than any -other tree, unless it is the Carolina poplar. It should never be severely -deheaded or, as it is popularly called, "dehorned" (fig. 21), as the stubs -will practically never heal over, and from these cuts decay will start, -which in a very few years will rot the center of the limbs and trunk and -thus destroy the tree. Although it forms a large round head with an open -top and its foliage is pale green above and almost white beneath, making -a very delightful shade, on account of its weaknesses it should never be -used for street planting where other trees can be made to grow. - -[46] _Acer saccharinum_ L. - -The sugar maple,[47] or hard maple, is especially adapted to gravelly -soils in regions 1, 10, and 11, the northern parts of regions 2 and 3, and -the eastern and southern parts of region 9. It is oval-headed, large, and -handsome, having red blossoms which individually are inconspicuous but -which in mass are showy early in the spring before the leaves appear. The -leaves come early, but in late summer they begin to turn brilliant yellow -and red and drop before most other leaves. The sugar maple does not thrive -under city conditions, but is admirably adapted to suburban conditions. - -[47] _Acer saccharum_ Marsh. - -Although the sycamore maple[48] is similar in appearance to the Norway -maple, it is not a satisfactory street tree in the eastern United States. -It succeeds, however, in regions 1, 2, 3, and 4. - -[48] _Acer pseudoplatanus_ L. - -[Illustration: P15662HP - -Fig. 22.--A sugar maple (on the left) and a white oak (on the right), each -32 years old and nearly the same size.] - - -OAK. - -Of the trees used for street planting the oaks are best. They probably -have not been more widely planted because of the prevalent belief that -they are slow growers and because in the North they are rather difficult -to transplant. Although some of the handsomest species, like the white oak -and live oak, are slow growers, those suitable for street planting are -comparatively rapid-growing. The white oak and sugar maple shown in figure -22 are each 32 years old and although differing in shape are practically -the same size, yet the sugar maple is considered a sufficiently -rapid-growing tree to be planted frequently as a street tree, while -the white oak is seldom so used. The oaks are hardy, most of them are -long lived, and for the most part they are free from disease and insect -attacks. Some of the southern species are subject to attacks of mistletoe. - -The California live oak[49] is an evergreen suitable for use in region 2 -and succeeds adjacent to the ocean. It is also useful in region 3 and in -the western part of region 5. It is easily transplanted if handled young, -and especially so when planted from pots. - -[49] _Quercus agrifolia_ Nee. - -The chestnut oak[50] is a native of gravelly soils on eastern mountains -and is suitable for gravelly soils in suburban locations in regions 9, 10, -and 11. It is a large, handsome tree. - -[50] _Quercus montana_ Willd. (formerly _Q. prinus_). - -The Darlington oak[51] is a form of laurel oak especially desirable for -street planting. It is large, round-headed; the leaves are a trifle -smaller and not quite so nearly evergreen as the laurel oak. It is -found wild about Darlington, S. C., where a good form of the laurel oak -appears to have been introduced as a shade tree in the early part of the -nineteenth century. (Fig. 23.) Its range of usefulness lies in regions 11 -and 12. - -[51] _Quercus laurifolia_ Michx. - -The laurel oak[52] is a large, oval-headed tree that is not as rugged and -irregular as the live oak, but is suitable for street planting in regions -11, 12, and 13. It has large, thick, glossy leaves, and in the warmer -regions it is almost evergreen. It is readily transplanted, but as it is -not so common in the woods as the willow oak and the water oak, it has not -been so much used as a street tree. - -[52] _Quercus laurifolia_ Michx. - -[Illustration: P15461HP - -Fig. 23.--A Darlington oak as seen in late summer, Darlington. S. C.] - -The live oak[53] (fig. 16) is probably the noblest and most majestic of -the oaks of regions 12 and 13. It is evergreen and of slow growth, but -wherever it is found, whether on streets or in public parks, it is the -pride of the people. Although an evergreen it is sufficiently open-headed -to make a good street tree. When it becomes old it is spreading and as -a rule does not form as high a head as the willow oak and the laurel -oak. Compared with other southern oaks it is difficult to transplant. -It is of sufficient merit to be used on broad streets, and especially -on boulevards, where the good of the future as well as the present is -considered. - -[53] _Quercus virginiana_ Mill. - -[Illustration: P14413HP - -Fig. 24.--A street shaded with red oaks, Washington, D. C.; midsummer.] - -The burr oak,[54] or mossy-cup oak, is native in the northeastern United -States and west of the Mississippi River on the hills lying between the -river bottoms and the prairies west to the western parts of the Dakotas -and Nebraska and central Kansas and Texas. It is a large; handsome tree -that should prove satisfactory under suburban conditions in regions 7, 8, -9, 10, and 11 and on fertile well-watered soils. - -[54] _Quercus macrocarpa_ Michx. - -The pin oak,[55] sometimes called the swamp oak, is a tall tree, conical -when young, oval at maturity, with a drooping habit of the lower branches. -The leaves are quite finely divided and are of a bright glossy green. -The tree comes into leaf late in the spring and holds its foliage late -in the fall. One objection to the pin oak for street planting is that on -many specimens the dead leaves hang on through the winter. It is adapted -to narrower streets than the red oak, as its habit of growth is not so -spreading. On account of the tendency of the limbs to droop, particularly -as they get older, it is desirable that a good strong leader should be -developed, so that the lower limbs may be removed from time to time as -conditions require. The pin oak thrives on wet and on heavy clay soils, as -well as on a wide range of other soils. Figure 4 shows pin oaks, Norway -maples, and ginkgos 18 years old on adjacent streets, and illustrates the -rapid growth of this oak. At the time of planting these trees the pin oaks -were thought to have the poorest location. This tree is adapted to regions -1, 2, 3, 4, 9, 10, and 11. - -[55] _Quercus palustris_ L. - -The red oak[56] (fig. 24) is probably the best tree for street planting -in regions 1, 9, 10, and 11 and is satisfactory in regions 6, 7, 8, and -12. It is a large, oval, open-headed tree of rapid growth. Under good -conditions a young red oak will grow 4 feet in a single season. Like the -other oaks it is slow in coming into leaf in the spring, but holds its -foliage late in the fall. The leaves usually turn a brilliant red before -they drop. It is comparatively free from insect and fungous attacks, and -it is one of the few trees really suitable for planting close to the -ocean, as it thrives on sandy lands only a few feet above high tide or -within the reach of ocean spray. - -[56] _Quercus maxima_ (March.) Ashe (formerly _Q. rubra_). - -The scarlet oak[57] is a large, open, round-headed tree. Its leaves are -more deeply divided than those of the red oak. As its name indicates, the -leaves turn a brilliant scarlet in autumn, being even more gorgeous than -the red oak. This tree is adapted for street planting and is especially -desirable for suburban conditions in regions 1, 9, and 10. - -[57] _Quercus coccinea_ Muench. - -The swamp Spanish oak[58] is adapted to regions 11, 12, and 13. It belongs -to the red oak group, but is larger than the other oaks suggested for -street planting. It is well adapted to suburban locations, but apparently -it has not been tested under severe city conditions. - -[58] _Quercus rubra_ L. (formerly _Q. falcata_, and certain forms -separated by some botanists as _Q. pagodaefolia_ Ashe). - -The valley oak[59] is a beautiful tree for regions 2 and 3 and the more -favorable parts of region 5. When transplanted young, especially if taken -from a pot, it is easily established where there is opportunity to water -it for a few years. - -[59] _Quercus lobata_ Nee. - -The water oak[60] is frequently confused with the willow oak and the -laurel oak, as these three oaks are not distinguished from one another -except by close observers of trees. It is probably more used than any -other tree in the cities of region 12 and the adjoining portions of region -11. It is the weed of the southern oaks and one of the weeds of the street -trees of the Southern States. It is comparatively short lived and seems -to be more subject to attacks of mistletoe and more easily affected by -windstorms than the willow oak, the Darlington oak, and the laurel oak. -The planting of this tree should be avoided, because it is less desirable -than the other oaks mentioned. - -[60] _Quercus nigra_ L. - -[Illustration: Fig. 25.--Leaves of some of the southern oaks; _A_, Live -oak; _B_, willow oak; _C_, laurel oak; and _D_, water oak.] - -The willow oak[61] (fig. 1), sometimes erroneously called the water oak, -is one of the best of the quick-growing oaks for use in regions 11 and -12. It is frequently used with the water oak for street planting and in -the mind of the average planter is confused with it. It is, however, a -distinct tree, which can be distinguished readily from the water oak. It -is longer lived and is its equal in every other respect. Trees of this -variety which apparently have been planted about 80 years are found in -excellent condition, while water oaks planted at the same time have either -entirely disappeared or are showing marked evidences of decline. Figure -25 shows the characteristic appearance of the leaves of these nearly -related species of oaks. That the willow oak is readily transplanted in -the South when of comparatively large size is proved by the success with -which trees 12 feet high are dug from the woods and planted on the street -(fig. 26). In the extreme South this tree is nearly half evergreen. Its -foliage does not assume the bright colors of the trees of the red oak -class. - -[61] _Quercus phellos_ L. - -[Illustration: P15321HP - -Fig. 26.--Recently transplanted willow oaks, showing trees taken from the -woods as they appeared near the end of the second summer. Montgomery, Ala.] - - -PALM.[62] - -[62] The palms are treated on the basis of notes furnished by Dr. O. F. -Cook, of the Bureau of Plant Industry. - -Several varieties of palms are used more or less for street planting in -regions 2, 3, 5, 12, and 13. Though sometimes effective as a formal street -decoration (fig. 27), they can hardly be considered shade trees. - - -PALMETTO. - -Palmettos, or sabals, abound in region 12 near the coast; succeed -in regions 3, 5, and 13; live in region 2; but are seldom grown -satisfactorily close to the Pacific coast. They can be used effectively -for formal plantings along some streets, park drives, or in liberal -central parking spaces in boulevards, but they are not useful as a -substitute for shade trees. They should have then leaves and damaged roots -cut off in transplanting and should be set about 3 feet deep in their new -location. - -The Carolina palmetto[63] is a native of and useful in regions 12 and 13, -where it sometimes attains a height of 60 or 80 feet. It will thrive in -regions 3 and 5, but is used less there. - -[63] _Inodes palmetto_ (Walt.) Cook. - -The Texas palmetto[64] is especially valuable for southern Texas, where it -is indigenous, and it is likely to succeed generally in regions 3, 5, and -12. It grows to a height of 40 feet and in appearance is quite distinct -from the Carolina palmetto, the leaf segments being much broader and less -drooping.[65] - -[64] _Inodes texana_ Cook. - -[65] The Texas palmetto. _In_ Jour. Heredity, v. 8, no. 3, p. 123, pl. -1917. - -[Illustration: P18989HP - -Fig. 27.--A formal planting on a city street. Palms with interplantings. -Redlands, Calif., in midsummer.] - -The Victoria palmetto[66] is another hardy species, probably a native of -Mexico, but grown for many years at Victoria, Tex. It is similar to the -native Texas species and worthy of general planting in the same region. -A feature of this species is that the persistent leaf bases remain alive -and green for many years instead of turning yellow or brown, as in the -Carolina palmetto. - -[66] Cook, O. F. A new ornamental palmetto in southern Texas. _In_ U. S. -Dept. Agr., Bur. Plant Indus. Cir. 113, p. 11-14. 1913. - - -WASHINGTONIA PALM. - -Washingtonia palms are a very conspicuous feature of street and -ornamental planting in southern California. Two species are represented, -_Washingtonia filifera_ Wendland and _W. robusta_ Wendland. The first is -a native of the canyons and barren slopes that surround the Coachella -Valley of southern California, while the other species probably was -brought by way of the Isthmus of Panama from the region of San Jose del -Cabo, the extremity of Lower California, in the early days of travel. -The name _robusta_ alludes to the fact that this species grows much more -rapidly in height than _W. filifera_, though the trunk is more slender. -Both species are hardy and thrive well through regions 2, 3, and 5, and -also in regions 12 and 13. _Washingtonia robusta_ requires less heat than -_W. filifera_, but both will endure several degrees of frost. Even in -California _Washingtonia robusta_ is distinctly preferable for localities -near the coast. In the vicinity of San Diego the leaves of _Washingtonia -filifera_ become badly infested with a parasitic fungus that does not -attack _Washingtonia robusta_. - - -OTHER HARDY FAN PALMS. - -The species most commonly used for street and ornamental planting in the -California coast districts is the Chinese or windmill palm.[67] This palm -has a slender trunk clothed with brown fibers, flat fan-shaped leaves, -and rather straight radiating segments. The same species is hardy at New -Orleans and Charleston, and even at Laurens, S. C., at an altitude of 600 -feet, but it does not thrive in the sandy soil of Florida. - -[67] _Trachycarpus excelsa_ (Thunb.) Wendl. - -The vegetable hair palm,[68] a native of Spain, Sicily, and North Africa, -is similar to the Chinese palm but smaller and more compact and with -large, sharp spines on the petioles of the leaves. When young it suckers -from the base, like the date palm, so that clusters of it may be formed. - -[68] _Chamaerops humilis_ L. - -The Guadeloupe Island palm[69] is one of the most popular species in -southern California in the region of Santa Barbara, Los Angeles, and San -Diego. This palm is a native of Guadeloupe Island, of! the coast of lower -California, and is not known to occur elsewhere in the wild state. It -is well adapted to the cool coast climate of California, but not to the -interior valleys. It is smaller than the Washingtonia palms, with a rather -short trunk, 15 to 20 feet high, and a dense crown of fresh green leaves. - -[69] _Erythea edulis_ (H. Wendl.) S. Wats. - -The California blue palm,[70] formerly placed in the same genus with -the Guadeloupe Island species, is very distinct in habits as well as -in general appearance, having bluish or grayish green leaves, strongly -toothed petioles, and long, slender inflorescences. The trunk is very -robust, often 2 to 3 feet in diameter, and is said to attain a height -of 30 to 40 feet in Mexico. Several of these features are shared with -the Washingtonia palms. It also has the ability to grow in the dry, hot -interior valleys (regions 3 and 5). In Texas the blue palm has proved -hardy at San Antonio, and even as far north as Austin. - -[70] _Glaucothea armata_ (formerly known as _Erythea armata_). See Cook, -O. F., Glaucothea, a new genus of palms from Lower California. _In_ Jour. -Washington Acad. Sci., v. 5, p. 236-241. 1915. - - -DATE PALM. - -The Canary Island date palm[71] is the most popular palm for park or -street planting, being more hardy than the true date palm, larger and more -vigorous in growth, and producing no suckers from the base of the trunk. -Well-grown specimens in the California coast districts (region 2) with -trunks from 2 to 3 feet thick and immense crowns of spreading deep-green -leaves are among the most imposing forms of plant life. Though less robust -in other regions, the species is very hardy and adapted for planting -anywhere in the palm belt (regions 3, 5, 12, and 13). - -[71] _Phoenix canariensis_ Hort. - -The true date palm[72] is adapted to the warmer parts of regions 3 and 5, -but it is much inferior to the Canary Island species for ornamental use -because the foliage is less attractive, due to its habit of sending out -suckers from the base of the trunk. - -[72] _Phoenix dactylifera_ L. - - -THE COCONUT AND ITS RELATIVES. - -The true coconut palm is confined to a narrow belt along the coast of -southern Florida, but other species of cocos are planted in the coast -districts of California. The species that is most prominent in park and -street plantings around San Diego, Los Angeles, and Santa Barbara is -usually known as _Cocos plumosa_ or _Cocos romanzoffiana_, and is a rather -tall, slender palm with a long-jointed trunk about 1 foot in diameter -and long, spreading, feathery, deep-green leaves. Another series is -represented by _Cocos yatay_ and several similar species, often called -_Cocos australis_ in nursery catalogues. They have short, thick trunks, -very glaucous grayish or bluish foliage, and fleshy edible fruits, highly -flavored, somewhat like pineapples. These gray-leaved species are very -hardy. Another coconut relative is the Chilean molasses palm,[73] which -has a massive trunk 3 or 4 feet in diameter, specimens of which are -growing at a few places in California. - -[73] _Jubaea chilensis_ Baill. - - -OTHER PINNATE PALMS. - -The amethyst palm, a native of Australia, is commonly planted in -California. It usually appears in lists and nursery catalogues as -_Seaforthia elegans_ or _Archontophoenix alexandrae_, but it is now -recognized as distinct from both of these species and has received a new -name, _Loroma amethystina_. It is the only pinnate-leaved palm, except -certain species of Phoenix and Cocos, that grows freely in the open air -in the coast districts of California, from Santa Barbara to San Diego. -In habit and general appearance Loroma is more like the royal palm, -though with a smaller trunk and fewer leaves. The pinkish purple drooping -inflorescence is very attractive and develops into a large cluster of -scarlet berries. - - -The royal palms, species of Roystonea, are perhaps the most striking -ornamental members of the whole group. They can be grown in southern -Florida and even exist in the wild state in some of the hammocks below -Miami. - - -PEPPER TREE. - -The California pepper tree[74] is much used in regions 2 and 3 and in the -western part of region 5. It is a moderate-sized broad-headed tree with -fine foliage, which gives it a light, airy appearance. During the fall -and winter it is covered with scarlet berries, which in contrast with the -persistent foliage produce a pleasing effect. - -[74] _Schinus molle_ L. - -[Illustration: Fig. 28.--A pavement heaved by the roots of poplar trees.] - - -POPLAR. - -Poplars are not desirable for street planting. Their wood is brittle and -easily broken by ordinary windstorms, and their roots run near the surface -and are likely to interfere with pavements, as shown in figure 28, while -those of some varieties are especially liable to make trouble in sewers -by filling them with a mass of fibrous roots if access is once gained. -Vigorous root growth is encouraged by the moisture from a leak, and the -roots ultimately find their way inside. - -The southern cottonwood,[75] Carolina poplar, and the northern -cottonwood[76] are so similar in their adaptability for street planting -purposes that they will be discussed together. They are easily propagated, -easily transplanted, are quick-growing, and where they reach maturity -under normal conditions form very large oval-headed handsome trees, but -under the artificial conditions existing in cities it is necessary to -prune them quite severely when young to remove the long vigorous growths -and make the heads more compact. This pruning stimulates more vigorous -growth, which must be removed or they will form long branches with heavy -tops, that are especially liable to be injured by windstorms. The more -they are pruned the greater the tendency to an undesirable form of growth. -They begin dropping their leaves early in the summer and lose them very -early in the autumn. Their root growth is especially vigorous, so that -they are liable to make trouble in sewers in the manner already mentioned. -It is largely on this account that many cities prohibit the planting of -these trees. Except in regions 6, 7, or 8 or in locations where smoke and -fumes in the air prevent the growing of other trees, they should not be -planted. - -[75] _Populus deltoides_ Marsh. - -[76] _Populus virginiana_ Fouger. - -The Lombardy poplar[77] is a tall columnar tree adapted for use on very -narrow streets (fig. 14). It is short lived in many places, due largely to -the European poplar canker, but otherwise is a satisfactory tree for these -conditions in all parts of the United States. The trees may be planted as -close together as 30 feet. - -[77] _Populus italica_ (Du Roi) Moench. - -None of the other poplars have much to recommend them for street planting. - - -RUBBER TREE. - -The rubber tree[78] is a large-headed handsome evergreen, suitable for -regions 3 and 5 and the southern parts of regions 2 and 13 when the use of -an evergreen tree is warranted. - -[78] _Ficus elastica_ Roxb. - - -SILK OAK. - -The silk oak,[79] or Australian fern, is a large, handsome tree that -succeeds well in regions 2, 3, and 13; also in region 5 if provided with a -reasonable amount of moisture, as it stands drought remarkably well. It is -covered in early summer with orange-colored flowers. - -[79] _Grevillea robusta_ A. Cunn. - - -SWEET GUM. - -The sweet gum[80] is adapted to regions 11, 12, and 13, especially on -sandy lands. It forms an oval-headed, handsome tree with star-shaped -leaves that assume a particularly brilliant hue in the autumn. It is -better adapted to suburban conditions than to the heart of a city. Toward -the northern limits of its successful cultivation it is difficult to -transplant, while in the warmer sections of the country it can be moved -with comparative ease. It should be transplanted only in the spring. - -[80] _Liquidambar styraciflua_ L. - - -SYCAMORE. - -The sycamore[81] also called the buttonwood and buttonball tree, is a -large, open, spreading, quick-growing tree native along water-courses. -It is adapted to regions 1, 2, 3, 4, 9, 10, 11, 12, and 13 and is worth -testing in regions 5, 6, 7, and 8. Its habit of shedding its outer bark -in large flakes, leaving the white new bark showing in large patches, -makes it a conspicuous tree wherever grown. The fruits are balls 1 inch -or more in diameter and are sometimes objected to because they make dirt -when falling; also the shed bark is considered objectionable. It is such -a strong-growing handsome tree and succeeds so well under city conditions -that it is being planted more and more frequently. It will stand more -pruning and shaping than any other street tree. Without pruning it is -too large for ordinary streets unless spaced at almost double the usual -planting distance, with the trees staggered along the street instead -of being planted opposite. Its high head and open habit of growth are -distinct advantages for street planting. Its foliage, too, is a light -green, which gives an impression of airiness with the shade. It is subject -to attack by a fungus that kills the leaves while still small or partially -mutilates them, giving them an unsightly appearance. In some places this -trouble is quite serious. - -[81] _Platanus occidentalis_ L. - -The California sycamore[82] is a native of California adapted to regions -1, 2, 3, and 4 and portions of region 5. It is similar in general -characteristics to the sycamore. - -[82] _Platanus racemosa_ Nutt. - -The London plane tree[83] is one of the Old World forms of sycamore. -According to Alfred Render,[84] "the true oriental plane is rare in -cultivation, the tree usually planted under this name being _Platanus -acerifolia_" It it more compact in habit of growth and has the other good -qualities of the sycamore. It is being more and more used on city streets -and is proving satisfactory in regions 1, 2, 3, 4, 9, 10, 11, and 12. It -will probably succeed in the warmer parts of regions 6 and 7 and also in -regions 5 and 8. It is a more desirable tree for ordinary use than the -sycamore, on account of its more compact habit and comparative freedom -from disease, though it is tender in the northernmost sections. - -[83] _Platanus acerifolia_ (Ait.) Willd. - -[84] Bailey, L. H., ed. New York, 1916. Standard Cyclopedia of -Horticulture, v. 5, p. 2707. - - -TULIP TREE. - -The tulip tree[85] is also sometimes called the tulip poplar or yellow -poplar, though the latter names are unfortunate, as the tree is not -a poplar or even closely related to the poplars. It is a large, -rapid-growing tree suitable for suburban conditions in regions 1, 2, 10, -11, and 12. The leaves are of unusual form, the upper half appearing to -have been cut away, leaving a notch about where it would seem the middle -of the leaf should be. The color is a light green. The roots are unusually -soft and tender, and therefore the tree needs to be transplanted quickly -and with great care. Small sizes should be planted, especially near the -northern limits of growth. It should be transplanted only in the spring. -If after transplanting it the top should die and a new vigorous shoot -should put out from the root, it would be desirable to form a new top from -this shoot rather than to transplant another tree. - -[85] _Liriodendron tulipifera_ L. - - - - -CULTURE OF STREET TREES. - - -SELECTION OF INDIVIDUAL TREES. - -Nursery-grown trees should be used for street planting, and they should -have been transplanted at least every two years while in the nursery. -This is to insure a thorough root pruning and the production of numerous -fibrous roots close to the trunk. Trees not frequently transplanted form -a few long roots that are largely cut off when the tree is dug. Trees -growing in the woods form a few very long roots, and when an attempt is -made to dig them only a little of the root next the trunk is obtained, -while most of the roots, including the fibrous ones, are left in the -ground. If woodland trees are wanted for street purposes, most kinds -should be grown for a few years in a nursery in order to form a good root -system before being planted on the streets. - -In addition to a good root system, the tree should have a straight -trunk for the variety, with a good set of branches, called the head, -the bottom branches being from 7 to 9 feet from the ground. Trees which -naturally head low should be started with a higher head than those -varieties that have a tendency to an upright growth. A good head for a -shade tree is a leader or upright branch with three or more side branches -about equally spaced around the tree. The trees should be healthy, free -from scars, and also free from evidences of insects or diseases. In the -presence of insects, trees should be thoroughly fumigated along approved -methods before leaving nurseries, to insure against the introduction and -distribution of pests. Weakened vitality resulting from transplanting and -subsequent neglect will frequently invite attack by bark-boring insects -which seriously damage or kill the trees. Mulching and watering will often -prevent this damage. - -Opinion as to the size to plant differs somewhat, but for average -conditions trees from 10 to 12 feet high and with trunks or stems from 2 -to 2-1/2 inches in diameter[86] are very satisfactory in most varieties -used for street purposes. With such varieties as elms sycamores, and some -southern oaks, somewhat larger trees can be used equally well, while -smaller trees would be better in the regions of limited rainfall both -east and west of the Rocky Mountains and for tulip trees and sweet gums, -especially in the northern portion of their range of usefulness. - -[86] Designated by nurserymen as "caliper." - - -PREPARATION OF HOLES. - -Next to the selection of a proper variety, the preparation of the hole -is the most important detail of street tree planting. Because of the -restricted area available for the spread of the tree roots, and owing to -the artificial conditions imposed by the improvement of city streets, the -soil provided for the feeding ground of the roots of the young tree must -be liberal in quantity and of the best quality. From 2 to 3 cubic yards of -soil should be provided for each tree. It is desirable to have at least 18 -square feet of opening in the sidewalk, especially if it is of concrete or -other impervious material. Trees will grow with smaller sidewalk openings, -but they are not likely to thrive so well, and it is impossible properly -to prepare a hole for planting a tree without disturbing at least this -much surface soil. The proper depth of soil is from 2-1/2 to 3 feet. A -hole 3 feet deep large enough to hold 2 cubic yards of soil has a surface -area of 18 square feet. A hole 6 feet long, 3 feet wide, and 3 feet deep -will hold 2 cubic yards of soil, will have the smallest desirable surface -area, and will be of such dimensions as will best conform to the usual -sidewalk and roadway widths and thus not interfere with traffic. - -The tree hole must be so drained that water will not stand in it. If the -soil is so impervious as to hold water some artificial drainage must be -provided. That portion of the depth of a hole that acts as a cistern for -holding water is valueless as a feeding ground for roots. For every cubic -foot of soil in the bottom of a hole that might thus be made valueless by -standing water, 1-1/2 cubic feet of soil should be added by increasing the -length or width of it. Under no circumstances, however, should the depth -of available feeding ground be less than 2 feet. The deeper the roots may -be encouraged to grow, the less injury is likely to be experienced from -drought. - -The soil used should be topsoil from land that has been producing good -crops. This should be well enriched with rotted manure, one part of manure -to four of soil. The addition of such fertilizers as ground bone, tankage, -fish scrap, or cottonseed meal at the rate of 1 pound to the cubic yard of -soil is also helpful. Commercial fertilizers containing mostly phosphoric -acid obtained from other substances than ground bone are not to be -recommended for use in the soil about the roots at planting time. When -used they should form a surface application, worked into the soil after -planting. - - -PLANTING. - -If trees are shipped from a distance they should be taken at once on -arrival to some point where the roots may be carefully covered with soil; -there they should be unpacked and plenty of loose moist earth worked -thoroughly around and over the roots as fast as they are taken from -the box. This temporary covering of the roots is called "heeling in." -(Fig. 29.) The tops may be either erect or laid almost on the ground in -successive rows, the tops of one row lying over the roots of the previous -rows, the object being to cover the roots thoroughly and keep them moist -until the tree is wanted for permanent setting. Not a moment of exposure -should be permitted between the box and the soil. If the roots appear dry, -they may be dipped for a few minutes before "heeling in" in a tub of water -or in thin mud. - -[Illustration: P20370HP - -Fig. 29.--Trees properly "heeled in."] - -[Illustration: P20000HP - -Fig. 30.--Trees handled in a careless manner. The roots should have been -covered with wet canvas.] - -Trees in large quantities are often packed directly in cars with a small -quantity of straw about the roots. When shipped in this way extra care -(compare figs. 30 and 31) must be exercised in taking the trees to the -point where they are to be heeled in. The wagon in which they are to be -hauled should have a tight box, and wet canvas should be tied tightly over -the load. The last is important, so that there may be no chance for the -roots to dry. - -When taking trees from the ground where they have been heeled in to the -place for planting, great care must also be exercised to see that the -roots are not exposed to sun or wind, but are kept closely covered with -moss, wet burlap, or canvas until planted. Lack of care in this matter -is a greater cause of loss in tree planting than carelessness in any -other particular. One city that has its own nursery and uses largely -trees that are supposed to be difficult to move, but is careful about not -exposing the roots for a moment (fig. 31), has a loss of less than 1 per -cent. If the roots once dry the trees will die, and it takes but a short -exposure to dry the roots. The holes should be prepared well in advance -of planting, so that no time will be lost when conditions are right for -putting the trees in the ground. - -[Illustration: P20350HP - -Fig. 31.--A load of trees and tree boxes. The roots are packed in wet moss -and a tree is not taken from the wagon until the planter and two shovelers -are at the hole where it is to be planted.] - -In regions 1, 10, 11, 12, and 13 (fig. 17) the best time for planting -deciduous street trees is the month or six weeks just preceding freezing -weather in the fall. The other desirable time for planting is as soon -after freezing weather is over in the spring as the ground is dry enough -for the mechanical operations. This should be as early as possible, as the -more opportunity there is for root growth before warm weather forces the -top into growth, the better the results are likely to be. In regions 6, 8, -and 9, where the ground freezes to a considerable depth, spring planting -is to be preferred to fall planting unless it is possible to drench the -soil thoroughly for a considerable distance around the trees at planting -time and after that to mulch the soil thoroughly and also to protect the -top from the effect of drying winter winds. Where mice abound they may be -harbored in the mulch and may girdle the tree. This may be prevented by -a collar of wire netting about the base of the trunk or by banking the -earth about it. The death of trees at the time of transplanting is due to -the drying out of either roots or tops before opportunity is given them -to become reestablished in their new locations. This drying may be due to -improper exposure at the time of digging or before packing (fig. 30), poor -packing, prolonged delay in delivery, improper handling between unpacking -and planting, or the existence of conditions conducive to excessive drying -out of the plant after setting. - -[Illustration: P14340HP - -Fig. 32.--A city nursery.] - -The atmosphere is continually claiming a tribute of moisture from all -living plants, whether the plant is in leaf and growing or is dormant. -Growing plants, and dormant plants under normal conditions, are able to -replace this moisture by absorption through the roots. In climates where -newly planted trees may obtain sufficient soil water to replace these -losses by drying, fall planting is best. Where the plants are unable to -get sufficient winter moisture, planting would better be done only in the -spring. Where the soil freezes to a depth greater than that to which the -plant roots extend, the supply of water is cut off from the roots and the -tree will be killed by drying out through evaporation from the top. Where -winter winds are very drying and the soil moisture is limited, evaporation -from the top is likely to be in excess of that supplied by the roots and -the tree is killed in the same way. - -[Illustration: Fig. 33.--Setting a tree: _A_, Measuring from the curb to -get the tree in line; _B_, filling the hole: _C_, placing the box; _D_, -fastening the box.] - -In regions normally adapted to fall planting, newly set trees may be -killed by a dry autumn followed by a dry winter with, high winds or by a -cold winter with so little snow that the ground freezes below the roots. -On the other hand, trees may often be successfully planted in the fall -where such practice is not usually successful by thoroughly mulching the -soil if freezing is the sole cause of the difficulty, or by drenching the -soil thoroughly and then mulching well if lack of moisture and high winds -are the causes of the trouble. Protection from the wind by wrapping the -trunk and large limbs with burlap or some other protecting material is -also desirable. - -After a liberal opening has been made in the specially prepared soil the -tree should be brought, preferably from the city's own nursery (fig. 32), -but if such a nursery has not been provided, then from among the newly -received trees that have been "heeled in" as already described. - -If the tree has been well handled and the roots carefully protected it is -ready for setting. It is desirable to immerse the roots in a thin mixture -of clay and water just before putting it in the hole if there is suspicion -that the roots have been exposed. This can be done before leaving the -nursery or "heeling in" ground, but the roots must be properly protected. -Any mutilated ends of roots should be removed, the top should be severely -pruned, as described later, and the tree should be placed in the hole in -line with the other trees (fig. 33, _A_) and at such a height that after -the filling is completed it will be about an inch deeper in the ground -than it was before transplanting. The roots should be spread out in as -near their original position as practicable, and soil should be carefully -worked in about them with the fingers, so that each rootlet may come in -contact with soil and not be crowded against other rootlets. When all the -roots have been placed and covered the soil should be thoroughly trampled -or tamped to bring the roots into as close contact as possible with it. -Then more soil should be put in and the ground again tamped. Of course, in -order to get satisfactory results the soil used for planting must not be -too wet or too dry. If the soil is in such a state as to hold together in -soggy masses and not spring apart again when squeezed in the hand, it is -too wet for planting. If the soil is too dry, it will not stay in contact -with the roots during the planting operations. A soil that is too dry may -be well-watered a day or two in advance of the planting, or if excessive -dryness does not make it difficult to handle, the tree may be planted and -then be thoroughly watered. After the watering 3 or 4 inches of loose -soil should be spread over the wet ground in order to prevent undue -evaporation. It should not be trampled or pounded in any way after the -water is applied. If trees planted in moist retentive soils are watered -after planting they should be provided with a mulch of similar earth. East -of the Missouri River trees planted in soil that is in good condition -usually do not need watering at the time of planting. - -Trees planted from pots, cans, or boxes should have the ball of earth -taken from the receptacle handled with care, so as not to break it further -than to loosen some of the roots on the outside of the ball; then the soil -should be as carefully placed about this ball and the loosened roots as -about the roots of trees without balls. Trees planted with balls need no -root pruning and little top pruning. - -[Illustration: P20367HP - -Fig. 34.--A pin oak trimmed for planting. Note the bad stubs (_A, A_) on -the left-hand side of the tree.] - -[Illustration: P20368HP - -Fig. 35.--A sycamore trimmed for planting. Well primed, without bad stubs.] - - -PRUNING. - -At planting time the trees should be so pruned as to remove from one-half -to three-fourths of the leaf buds. The head should be formed in the -nursery, so that at planting time the only problem is how to reduce the -amount of prospective growth the first season without destroying the form -of the head. Specific directions are difficult, because different species -of trees are so different in their character of growth. A species that -is naturally compact in growth (fig. 34) should be pruned by removing -whole branches rather than by having the ends of branches removed. One -that is open and spreading (fig. 35) will probably need the shortening -of the longer limbs as well as the removal of interior branches. The -first pruning should be the removal of such branches as can be spared. -If enough buds can not be removed in this way without leaving the head -too open, then the shortening of the branches must follow. It is usually -necessary to remove three-fourths of the limbs to accomplish this. An -expert can do this pruning or most of it more easily before the tree is -planted than afterwards. Some additional pruning may be necessary after -the tree is set. - -In addition to the pruning of the top the roots may need some cutting. -Any broken pieces or ends should be removed, making a clean cut with a -sharp knife, as new rootlets put out more readily from a cleanly cut fresh -surface than from ragged breaks. If the roots are very long, without -branches or rootlets, it sometimes makes planting easier to cut off some -of the ends. As roots are the braces by which a tree is supported in the -ground, it is undesirable to reduce their length unless some positive good -is to be gained by it. - -[Illustration: P20372HP - -Fig. 36.--Types of tree guards.] - -The best implement for cutting small limbs is a sharp knife, and for -larger limbs a fine-toothed saw. Pruning shears are sometimes used, but -they are likely to bruise the wood. If used at all, the blade should -always be turned toward the tree so that the bruise made by the supporting -bar will be on the portion cut off. Where branches are taken off, the cut -should be close to the remaining limb, so that no suggestion of a stub -will remain. (Figs. 34 and 35.) Where ends are cut from branches the cut -should be just above a bud, and the remaining bud should point in the -direction that it is desired the limb should grow. - - -STAKES AND GUARDS. - -Under city conditions young trees need the support of a strong stake as -well as protection for the trunk. Boys like to swing around small trees -or see the tops fly up if bent to the ground. Men find them convenient -hitching posts for their horses, and horses frequently like the taste of -the bark or tear it off for the sake of having something to do. - -Guards are of many forms (fig. 36), from stakes 2-1/2 inches square set 3 -feet in the ground and extending 6 feet above, with heavy-netting placed -about the tree and stapled to the stake, to heavy wooden cribs of four -stakes and intermediate slats and wrought-iron patterns of many forms. - -The trees should be firmly secured to the tops of the guards so that they -will not swing against them in the wind and be rubbed. This is best done -by securing the tree in place in the guard by two loops of pieces of old -garden hose, soft leather, or rope, in such a way as not to bind the tree -too tightly while keeping it from swinging much or rubbing. The essentials -are a firm support for the tree while young with reasonable protection of -the trunk from careless depredations until the tree has reached a diameter -of 6 inches or more. - - -LATER CARE. - -If after planting, the season is dry and it becomes necessary to apply -water, the ground should be soaked thoroughly, and as soon as it has dried -sufficiently to work up loosely it should be hoed or raked to make a good -earth mulch. A mulch of strawy manure or litter may be used in place of -the earth mulch if desired. The watering should not require repeating for -a week or more. - -If the weather becomes warm soon after planting and the trees come into -leaf, wither, and droop, further pruning may save them. The reason for the -difficulty is probably that the growth of the top has been greater than -the newly formed roots can support; therefore the additional pruning is -likely to restore the balance between the top growth and root growth. At -least three-fourths of the remaining young wood should be removed. This -may leave the tree looking almost like a bean pole, but if it induces a -vigorous root growth the top can easily be re-formed. - -Young trees should have an annual inspection, and all crossing branches -and any that are not well placed to form a good head should be removed. -Attention should be given also to all forks, and where two branches start -almost parallel to one another or at a small angle, making a fork liable -to split apart as the tree grows, one branch should be removed. Where -three branches start from almost the same point there is little likelihood -of their splitting apart, but with only two growing at a less angle than -30° there is liable to be trouble in the case of most kinds of trees. On -trees on which few but long shoots form, it may be well to remove the ends -of such shoots. As a rule, it is undesirable to use for street planting -trees with this kind of growth. Young trees should be trained into a -desirable shape by the use of a pruning knife each year, so that a saw -will not be necessary later. Some trees have a tendency to form too dense -a head. The interior branches of these should be removed and the head made -as open as possible while the work can be done with a knife. No attempt -should be made to alter the natural form of a tree but only to insure its -best development. A skillfully pruned young tree will show no evidences of -the pruning after three or four years. - - - - -CARE OF MATURE TREES. - - -PRUNING. - -It is very little trouble to train a tree into a good shape by using the -pruning knife while the limbs are small, but it is usually difficult -to re-form a tree after it has grown to maturity. One who understands -tree growth, however, can often reshape the top of a neglected tree to -advantage, though many who make a business of tree trimming know so little -about it that they do more harm than good. More mature trees have been -hurt by severe pruning than have been helped. Of course, dead or dying -wood should be removed whenever it is found, no matter what the age of -the tree. This should be done by cutting off the limb back to the nearest -healthy crotch. A limb should not be cut off square across (fig. 21) -unless the tree is apparently in a dying condition and the whole top is -treated thus in an attempt to save its life. In such a case, a second -pruning should follow within two years, at which time the stubs left at -the first trimming should be cut off in a proper manner near the newly -started limbs. Healthy silver maples and willows are frequently cut in -this way, but the maples in particular would better be cut down at once -than to subject the public to the dangers of the insidious decay that -almost always follows such an operation on these trees and completes their -destruction promptly. - -Trees that have been neglected a long time frequently have interfering -or crossing branches, or are too low headed or too densely headed for -the place where they are growing. Defects of this kind may be at least -partially remedied. The removal of limbs by cutting them off at a crotch -in such a manner that the wound is parallel with the remaining branch -(fig. 37) inflicts the least possible damage. Such a wound in a healthy -tree will soon heal over if the cut is made through the slight collar or -ring that is nearly always present at the base of a branch. The closer -this cut can be made to the trunk the better the appearance when the cut -is healed. The closer the cut the larger the wound, but the difference -is unimportant if the wood is well protected until it is healed. These -operations are entirely different in purpose and result from the "heading -in" or "heading back" so often practiced under the guise of tree pruning, -either from a false notion of forming a top or for the passage of wires. - -Changing the form of a tree by pruning should not be attempted. Each -species has its own form or forms, and no attempt should be made to -change or distort a tree from its normal habit of growth. Successful -pruning will accentuate rather than disguise a tree's characteristics. - -[Illustration: P20371HP - -Fig. 37.--Part of a tree trunk showing proper and improper methods of -removing old limbs. Although healing has started on the stub (at the -right) it is likely to proceed very slowly. The nearer the cut is to the -tree the larger the wound but the less conspicuous the stub will be when -healed.] - -All cuts should be made so that no stubs or protuberances are left to -prevent quick healing. Small wounds need no after treatment if the cut -is well made. Large wounds should have the wood of the center of the -cut well protected to prevent decay until the new growth has had an -opportunity to heal over the cut. An application made to the center of the -cut to preserve the wood should not be permitted to come near the cambium -layer or inner bark, especially of soft-wooded trees like the tulip and -magnolia, as the oil or other substances contained in the paint, tar, or -other covering may spread to the cambium layer and kill it. It is well not -to make any application within half an inch of the outside of the wound -unless the coating has been thoroughly tested. - -Dead wood should be entirely removed, the cut being made through good live -tissue. Removing such wood frequently exposes decayed cavities, usually -from bad stubs or injuries which have started decay that has followed back -to the main limbs or the trunk. The treatment of such cavities is the -province of tree surgery and is discussed in another publication.[87] - -[87] Collins, J. F. Practical tree surgery. _In_ U. S. Dept. Agr. -Yearbook, 1913, pp. 163-190, pl. 16-22. Published as Yearbook Separate -622, obtainable from the Superintendent of Documents for 10 cents in coin. - -One source of trouble with a large tree that has developed with two trunks -or branches instead of three or more is the liability of their splitting -apart in the crotch. This is especially characteristic of the elm. Careful -attention to the early pruning of trees may eliminate this defect, but -when it exists in mature trees it is frequently advisable to connect the -branches by a strong chain (fig. 18) in order to prevent the limbs from -being torn apart. - - -FEEDING. - -It is difficult to do anything to stimulate the growth of street trees -after they are once started, because usually the only uncovered area over -the roots is the small opening immediately about the tree; hence, the -importance of supplying the best of soil well enriched at the time of -planting. Sometimes a stimulation is desirable, which can be accomplished -by dissolving one-half to 1 pound of nitrate of soda in 50 gallons of -water and applying from 1 to 25 gallons of the liquid, depending on the -size of the tree. Unless the soil is damp at the time of application water -will be needed immediately afterward. This material should be applied only -when the tree is in full leaf and growing. If applied when the tree is -dormant it is likely to be leached from the soil before it is absorbed. -If applied late in the season, that is, within three months of freezing -weather, it would likely stimulate a late growth that would be liable -to be killed the following winter and might make the whole tree more -susceptible to injury from cold. - -Water is one of the great needs of city trees, as the ground surface is -often almost completely roofed over with water-tight coverings. It is -usually a help for the pavement washings to drain into the parking space -where the tree is planted. If a curb is placed about the parking space, -frequent, regular watering is necessary where the ground is thoroughly -covered with water-tight pavements. - -Where growing under suburban conditions, that is, with streets partially -pervious to water, liberal parking spaces, and adjoining lawns, street -trees will respond to all extra care given the near-by open spaces, -whether parkings, lawns, or gardens. If these are well cared for the trees -should have ample sustenance from them without any direct applications. - -In order to prevent the soil about a tree from being packed too hard by -trampling it is frequently desirable on business streets to cover the soil -about it with an iron grating. - - -SPRAYING. - -Street trees, like all other forms of vegetation, are subject to attacks -of insects and diseases. Because of the unfavorable conditions under which -they grow, spraying for biting and sucking insects and suitable treatment -for borers or other burrowing insects require especially careful attention. - -In addition to a number of troubles common to street trees in general, -each species is liable to troubles of its own; hence, the need of -competent supervision by a trained man with an efficient outfit rather -than leaving; the work to individual initiative. - -Because of the height which many street trees attain a powerful outfit is -required to spray them properly. One capable of maintaining a pressure -of 200 pounds per square inch is desirable. The type of spray required -for tall trees is different from that used on fruit trees and other -low plants. For low trees the ideal spray is a mist within a few feet -of the nozzle, application being accomplished by having the nozzles -near the foliage to be treated. For tall trees it is desirable that the -liquid should leave the nozzle in a solid stream, which is broken into -spray as it passes through the air. The material has to be projected -with sufficient force to reach the highest trees before being entirely -converted into mist, as it is impracticable to extend the nozzles into -the trees to reach the farthest portions, as is done with fruit and other -low trees. The spray can not be applied as uniformly as a mist, but it -is impracticable to climb into the tops of shade trees to cover every -part with a cloudlike spray. On the other hand, the mist spray is better -for small trees, as much injury may be done to low trees or to the lower -branches of high trees by the force of the stream from high-pressure -outfits. - -It is estimated that in practice up to 95 per cent of the attacking -insects can be killed with insecticides carefully applied by the stream -method under high pressure. - -In addition to the mechanical problem of satisfactorily covering high -trees with insecticides or fungicides there is the problem of selecting -materials that will be effective against the insects and diseases and -at the same time will not disfigure the paint or stone work of adjacent -buildings with which the materials must inevitably come in contact in -street tree spraying. It frequently happens that the most effective -remedies must be rejected because of the damage they would do to buildings -and that less efficient materials must be used. - -Whitewashing the trunks of trees is a useless and unsightly -practice--useless, as it does not prevent the attacks of insects, and -unsightly, because it makes the trunks of the trees obtrusive when they -should be inconspicuous. - -Banding with cotton or proprietary preparations may occasionally be -useful, but because such applications are so seldom helpful and because -some of the preparations result in injury due to constriction of the -trunks, it should not be resorted to except upon special recommendation of -an entomologist familiar with the existing conditions. - -Details as to enemies to be expected, methods of treatment, and materials -to be used may be found in other publications[88] or may be obtained by -correspondence with the nearest State agricultural experiment station or -with the United States Department of Agriculture. - -[88] See list on following pages. - - * * * * * - - PUBLICATIONS OF THE UNITED STATES DEPARTMENT OF AGRICULTURE - RELATING TO DISEASES AND INSECTS AFFECTING SHADE AND ORNAMENTAL TREES. - - =AVAILABLE FOR FREE DISTRIBUTION.= - - Control of Root-Knot. (Farmers' Bulletin 648.) - - The San Jose Scale and Its Control. (Farmers' Bulletin 650.) - - The Bagworm, an Injurious Shade-Tree Insect. (Farmers' Bulletin 701.) - - The Catalpa Sphinx. (Farmers' Bulletin 705.) - - The Leopard Moth: A Dangerous Imported Enemy of Shade Trees. - (Farmers' Bulletin 708.) - - The Oyster-Shell Scale and the Scurfy Scale. (Farmers' Bulletin 723.) - - The White-Pine Blister Rust. (Farmers' Bulletin 742.) - - Carbon Disulphid as an Insecticide. (Farmers' Bulletin 799.) - - The Gipsy Moth and the Brown-Tail Moth and Their Control. (Farmers' - Bulletin 845.) - - Common White Grubs. (Farmers' Bulletin 940.) - - The Blights of Coniferous Nursery Stock. (Department Bulletin 44.) - - Forest Disease Surveys. (Department Bulletin 658.) - - =FOR SALE BY THE SUPERINTENDENT OF DOCUMENTS, - GOVERNMENT PRINTING OFFICE, - WASHINGTON, D. C.= - - The Mistletoe Pest in the Southwest. (Bureau of Plant Industry - Bulletin 166.) Price, 10 cents. - - The Death of Chestnuts and Oaks Due to Armillaria mellea. - (Department Bulletin 89.) Price, 5 cents. - - New Facts Concerning the White-Pine Blister Rust. (Department - Bulletin 116.) Price, 5 cents. - - The Huisache Girdler. (Department Bulletin 184.) Price, 5 cents. - - Report on the Gipsy Moth Work in New England. (Department Bulletin - 204.) Price, 30 cents. - - A Disease of Pines Caused by Cronartium pyriforme. (Department - Bulletin 247.) Price, 5 cents. - - Food Plants of the Gipsy Moth in America. (Department Bulletin 250.) - Price, 10 cents. - - Dispersion of Gipsy Moth Larvę by the Wind. (Department Bulletin - 273.) Price, 15 cents. - - The Cottonwood Borer. (Department Bulletin 424.) Price, 5 cents. - - Solid-Stream Spraying against the Gipsy Moth and the Brown-Tail Moth - in New England. (Department Bulletin 4.80.) Price, 15 cents. - - Protection from the Locust Borer. (Department Bulletin 787.) Price, - 5 cents. - - Principal Insects Liable to be Distributed on Nursery Stock. - (Entomology Bulletin 34, n. s.) Price, 5 cents. - - The Locust Borer. (Entomology Bulletin 58, part 1.) Price, 5 cents. - - Additional Data on the Locust Borer. (Entomology Bulletin 58, part - 3.) Price, 5 cents. - - The San Jose or Chinese Scale. (Entomology Bulletin 62.) Price, 25 - cents. - - Report on Field Work against the Gipsy Moth and the Brown-Tail Moth. - (Entomology Bulletin 87.) Price, 35 cents. - - The Importation into the United States of the Parasites of the Gipsy - Moth and the Brown-Tail Moth. (Entomology Bulletin 91.) Price, 65 - cents. - - The Dispersion of the Gipsy Moth. (Entomology Bulletin 119.) Price, - 20 cents. - - The Green-Striped Maple Worm. (Entomology Circular 110.) Price, 5 - cents. - - The Oak Pruner. (Entomology Circular 130.) Price, 5 cents. - - The Dying Hickory Trees: Cause and Remedy. (Entomology Circular - 144.) Price, 5 cents. - - Flour Paste as a Control for Red Spiders and as a Spreader for - Contact Insecticides. (Entomology Circular 166.) Price, 5 cents. - - Three Undescribed Heart-Rots of Hardwood Trees, Especially of Oak. - (Journal of Agricultural Research, vol. 1, No. 2.) Price, 25 - cents. - - A Serious Disease in Forest Nurseries Caused by Peridermium - filamentosum. (Journal of Agricultural Research, vol. v, No. 17.) - Price, 10 cents. - - The Chestnut Bark Disease. (Separate 598, from Yearbook of the - Department of Agriculture for 1918.) Price, 10 cents. - - Practical Tree Surgery. (Separate 622, from Yearbook of the - Department of Agriculture for 1913.) Price, 10 cents. - - Forest Tree Diseases Common in California and Nevada. (Forest - Service Unnumbered Publication.) Price, 25 cents. - - - ADDITIONAL COPIES - - OF THIS PUBLICATION MAY BE PROCURED FROM - - THE SUPERINTENDENT OF DOCUMENTS - - GOVERNMENT PRINTING OFFICE - - WASHINGTON, D. C. - - AT - - 15 CENTS PER COPY - - - - * * * * * - - - -Transcriber Notes - - -Illustrations were moved so as to not split paragraphs. - - - - - -End of the Project Gutenberg EBook of USDA Bulletin No. 816, by F. L. Mulford - -*** END OF THIS PROJECT GUTENBERG EBOOK USDA BULLETIN NO. 816 *** - -***** This file should be named 62677-8.txt or 62677-8.zip ***** -This and all associated files of various formats will be found in: - http://www.gutenberg.org/6/2/6/7/62677/ - -Produced by Tom Cosmas -Updated editions will replace the previous one--the old editions will -be renamed. - -Creating the works from print editions not protected by U.S. copyright -law means that no one owns a United States copyright in these works, -so the Foundation (and you!) can copy and distribute it in the United -States without permission and without paying copyright -royalties. 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L. Mulford, a Project Gutenberg eBook. - </title> - <style type="text/css"> - -body {margin-left: 10%; margin-right: 10%;} - -p {margin-top: .75em; text-align: justify; - margin-bottom: .75em; text-indent: 1.5em;} -p.double {width: 60%; margin: 2em auto; border-top-style: double;} - -hr {width: 33%; margin-top: 1em; margin-bottom: 1em; - margin-left: auto; margin-right: auto; clear: both;} - -hr.chap {width: 65%; margin-top: 2em;} -hr.tb {width: 45%;} - -table {margin-left: auto; margin-right: auto; text-align: center; border-collapse: collapse;} -.tblcont tr:hover {background-color: #f5f5f5;} - -.pagenum {position: absolute; right: 3.5%; font-style: normal; /* prevent italics, etc. */ - font-size: small; text-align: right; color: #808080;} /* page numbers */ -.bbox {border: solid #000 1px;} - -.smcap {font-variant: small-caps;} -.center {text-align: center; margin:0; text-indent: 0;} -.vsmall {font-size: 0.5em;} -.smaller {font-size: 0.8em;} -.tdl {text-align: left;} -.tdr {text-align: right;} -.p0 {text-indent: 0; text-align: left;} -.ind3em {padding-left: 3em; text-indent: 0;} -h1, h2, h3, .caption2, .caption3, .caption4 {font-weight: bold; text-align: center; text-indent:0;} -h1 {font-size:2.00em; margin-top: 1.5em;} -h2, .caption2 {font-size:1.50em; margin-top: 1.0em;} -.caption2nb {font-size:1.50em; text-indent:0; margin-top: 1.0em;} -h3, .caption3 {font-size:1.25em; margin-top: 0.75em;} -.caption4 {font-size:1.15em; margin-top: 0.5em;} -.pmb2 {margin-bottom: 2em;} - -/* Images */ - -.fig_center {margin: auto; text-align: center;} - -.fig_left {float: left; clear: left; margin-left: 0; - margin-bottom: 1em; margin-top: 1em; - margin-right: 1em; padding: 0; text-align: center;} - -.fig_right {float: right; clear: right; margin-left: 1em; - margin-bottom: 1em; margin-top: 1em; - margin-right: 0; padding: 0; text-align: center;} - -.fig_caption {clear: both; font-size: 0.8em; margin-bottom: 1em; text-indent: 0; - margin-left: 2em; text-indent: -2em; text-align: left;} - -.phnum {float: right; font-size: 0.6em;} - - -.blockqtsm p {margin: 0 1.5em; font-size: 0.85em;} -.blockquot p {text-indent: 0; margin-left: 2em; text-indent: -2em; text-align: left;} -.vtop {vertical-align: top;} -.dropcap {float: left; padding-right: 0.5em; font-size: 2em;} - -/* Transcriber's notes */ -.trans_notes {background-color: #e6e6fa; color: black; padding:1.5em; - margin-bottom:5em;} - -/* Footnotes */ -.footnote {margin-left: 10%; margin-right: 10%; font-size: 0.9em;} -.footnote .label {position: absolute; right: 84%; text-align: right;} -.fnanchor {vertical-align: super; font-size: .8em; text-decoration: none;} - -sup {font-size: .6em; position: relative; top: 0.2em; left: 0.3em;} -sub {font-size: .6em; position: relative; top: -0.2em; right: 0.3em;} - - - </style> - </head> -<body> - - -<pre> - -The Project Gutenberg EBook of USDA Bulletin No. 816, by F. L. Mulford - -This eBook is for the use of anyone anywhere in the United States and most -other parts of the world at no cost and with almost no restrictions -whatsoever. You may copy it, give it away or re-use it under the terms of -the Project Gutenberg License included with this eBook or online at -www.gutenberg.org. If you are not located in the United States, you'll have -to check the laws of the country where you are located before using this ebook. - -Title: USDA Bulletin No. 816 - Street Trees - -Author: F. L. Mulford - -Release Date: July 16, 2020 [EBook #62677] - -Language: English - -Character set encoding: ISO-8859-1 - -*** START OF THIS PROJECT GUTENBERG EBOOK USDA BULLETIN NO. 816 *** - - - - -Produced by Tom Cosmas - - - - - -</pre> - - - - - -<div class="fig_center" style="width: 285px;"> -<img src="images/cover.jpg" width="285" height="468" alt="" /> -</div> - - -<hr class="chap" /> - - - - -<div style="width: 36em; border: solid #000 4px; padding: 4px; margin: 2em auto;"> -<div style="width: 35em; margin: 2px auto;" class="bbox"> -<p class="caption4">UNITED STATES DEPARTMENT OF AGRICULTURE</p> - -<p class="caption3">BULLETIN No. 816</p> - -<p class="center">Contribution from the Bureau of Plant Industry</p> - -<p class="center"><span class="smcap">Wm. A. Taylor</span>, Chief</p> - -<table style="width: 100%; border-top: solid #000 1px; border-bottom: solid #000 1px;" summary="list"> -<tr> - <td class="tdl" style="width: 8em;">Washington, D. C.</td> - <td class="center"> ▼ </td> - <td class="tdr" style="width: 8em;">January 19, 1920</td> -</tr> -</table> - - - -<h1>STREET TREES</h1> - - -<p class="center">By</p> - - -<h2>F. L. MULFORD, Horticulturist</h2> - - -<p class="caption4">Office of Horticultural and<br /> -Pomological Investigations</p> - - - -<p style="width: 100%; border-top: solid #000 1px; padding-top: 1.5em;" class="caption2">CONTENTS</p> - -<div class="tblcont"> -<table style="width: 25em;" summary="ToC"> -<tr> - <td></td> - <td class="tdr smaller">Page</td> -</tr> -<tr> - <td class="tdl">Importance of Shade Trees</td> - <td class="tdr"><a href="#IMPORTANCE_OF_SHADE_TREES">1</a></td> -</tr> -<tr> - <td class="tdl">Public Control of Street Trees</td> - <td class="tdr"><a href="#PUBLIC_CONTROL_OF_STREET_TREES">6</a></td> -</tr> -<tr> - <td class="tdl">Planning for Trees on City Streets</td> - <td class="tdr"><a href="#PLANNING_FOR_TREES_ON_CITY_STREETS">8</a></td> -</tr> -<tr> - <td class="tdl">Spacing Trees</td> - <td class="tdr"><a href="#SPACING_TREES">9</a></td> -</tr> -<tr> - <td class="tdl">Conditions for Tree Growth</td> - <td class="tdr"><a href="#CONDITIONS_FOR_TREE_GROWTH">10</a></td> -</tr> -<tr> - <td class="tdl">Kinds of Trees Suitable for City Streets</td> - <td class="tdr"><a href="#KINDS_OF_TREES_SUITABLE_FOR_CITY_STREETS">14</a></td> -</tr> -<tr> - <td class="tdl"><span style="margin-left: 1em;">Qualities Necessary</span></td> - <td class="tdr"><a href="#QUALITIES_NECESSARY">14</a></td> -</tr> -<tr> - <td class="tdl"><span style="margin-left: 1em;">Trees for Different Regions</span></td> - <td class="tdr"><a href="#TREES_FOR_DIFFERENT_REGIONS">20</a></td> -</tr> -<tr> - <td class="tdl">Descriptions of Street Trees</td> - <td class="tdr"><a href="#DESCRIPTIONS_OF_STREET_TREES">20</a></td> -</tr> -<tr> - <td class="tdl">Culture of Street Trees</td> - <td class="tdr"><a href="#CULTURE_OF_STREET_TREES">43</a></td> -</tr> -<tr> - <td class="tdl"><span style="margin-left: 1em;">Selection of Individual Trees</span></td> - <td class="tdr"><a href="#SELECTION_OF_INDIVIDUAL_TREES">43</a></td> -</tr> -<tr> - <td class="tdl"><span style="margin-left: 1em;">Preparation of Holes</span></td> - <td class="tdr"><a href="#PREPARATION_OF_HOLES">44</a></td> -</tr> -<tr> - <td class="tdl"><span style="margin-left: 1em;">Planting</span></td> - <td class="tdr"><a href="#PLANTING">45</a></td> -</tr> -<tr> - <td class="tdl"><span style="margin-left: 1em;">Pruning</span></td> - <td class="tdr"><a href="#PRUNING">50</a></td> -</tr> -<tr> - <td class="tdl"><span style="margin-left: 1em;">Stakes and Guards</span></td> - <td class="tdr"><a href="#STAKES_AND_GUARDS">51</a></td> -</tr> -<tr> - <td class="tdl"><span style="margin-left: 1em;">Later Care</span></td> - <td class="tdr"><a href="#LATER_CARE">52</a></td> -</tr> -<tr> - <td class="tdl">Care of Mature Trees</td> - <td class="tdr"><a href="#CARE_OF_MATURE_TREES">53</a></td> -</tr> -<tr> - <td class="tdl"><span style="margin-left: 1em;">Pruning</span></td> - <td class="tdr"><a href="#PRUNING1">53</a></td> -</tr> -<tr> - <td class="tdl"><span style="margin-left: 1em;">Feeding</span></td> - <td class="tdr"><a href="#FEEDING">55</a></td> -</tr> -<tr> - <td class="tdl"><span style="margin-left: 1em;">Spraying</span></td> - <td class="tdr"><a href="#SPRAYING">55</a></td> -</tr> -</table> - - -<div class="fig_center" style="width: 98px;"> -<img src="images/cover_logo.png" width="98" height="137" alt="" /> -</div> - -<p class="caption4">WASHINGTON<br /> -GOVERNMENT PRINTING OFFICE<br /> -<br /> -1920<br /> -</p> -</div> -</div> -</div> - -<p class="caption4"><b>BUREAU OF PLANT INDUSTRY.</b></p> - -<div style="width:25em; margin: 2em auto;"> -<div class="ind3em"> -<span class="smcap">William A. Taylor</span>, <i>Chief</i>.<br /> -<span class="smcap">K. F. Kellerman</span>, <i>Associate Chief</i>.<br /> -<span class="smcap">James E. Jones</span>, <i>Assistant to Chief</i>.<br /> -<span class="smcap">J. E. Rockwell</span>, <i>Officer in Charge of Publications</i>.<br /> -</div> -</div> - -<p class="center pmb2"><span class="smcap">Office of Horticultural and Pomological Investigations.</span><br /> -<br /> -SCIENTIFIC STAFF.<br /> -<br /> -<span class="smcap">L. C. Corbett</span>, <i>Horticulturist in Charge</i>.<br /> -</p> - -<table style="margin-bottom: 4em;" summary="list"> -<tr> - <td class="vtop"> - -<p class="p0">Truck Crop Production Investigations:</p> - -<p class="ind3em"> -J. H. Beattie.<br /> -F. E. Miller.<br /> -C. J. Hunn.<br /> -B. J. McGervey.<br /> -</p> - -<p class="p0">Irish Potato Production Investigations:</p> - -<p class="ind3em"> -William Stuart.<br /> -C. F. Clark.<br /> -W. C. Edmundson.<br /> -P. M. Lombard.<br /> -J. W. Wellington.<br /> -L. L. Corbett.<br /> -</p> - -<p class="p0">Truck Crop Improvement Investigations:</p> - -<p class="ind3em"> -W. W. Tracy.<br /> -D. N. Shoemaker.<br /> -</p> - -<p class="p0">Landscape Gardening and<br /> Floriculture Investigations:</p> - -<p class="ind3em"> -F. L. Mulford.<br /> -W. Van Fleet.<br /> -</p> - -<p class="p0">Bulb Culture Investigations:</p> - -<p class="ind3em"> -David Griffiths.<br /> -</p> - -<p class="p0">Fruit and Vegetable Utilization Investigations:</p> - -<p class="ind3em"> -J. S. Caldwell.<br /> -C. A. Magoon.<br /> -C. W. Culpepper.<br /> -</p> - - </td> - <td> - -<p class="p0">Fruit Production Investigations:</p> - -<p class="ind3em"> -H. P. Gould.<br /> -L. B. Scott.<br /> -C. F. Kinman.<br /> -George M. Darrow.<br /> -E. D. Vosbury.<br /> -</p> - -<p class="p0">Grape Production Investigations:</p> - -<p class="ind3em"> -George C. Husmann.<br /> -Charles Dearing.<br /> -F. L. Husmann.<br /> -Elmer Snyder.<br /> -G. L. Yerkes.<br /> -</p> - -<p class="p0">Fruit Breeding and Systematic<br /> Investigations in Pomology:</p> - -<p class="ind3em"> -W. F. Wight.<br /> -Magdalene R. Newman.<br /> -</p> - -<p class="p0">Fruit Improvement through Bud Selection:</p> - -<p class="ind3em"> -A. D. Shamel.<br /> -</p> - -<p class="p0">Nut Investigations:</p> - -<p class="ind3em"> -C. A. Reed.<br /> -E. R. Lake.<br /> -</p> - -<p>Fruit and Vegetable Storage Physiology:</p> - -<p class="ind3em"> -L. A. Hawkins.<br /> -R. C. Wright.<br /> -J. R. Magness.<br /> -J. F. Fernald.<br /> -</p> - </td> -</tr> -<tr> - <td colspan="2"> - <p class="center">Extension Work (in cooperation with States Relations Service):<br /> - W. R. Beattie.<br /> - C. P. Close.<br /> - </p> - </td> -</tr> -</table> - - - -<p><span class="pagenum"><a name="Page_1" id="Page_1">« 1 »</a></span></p> - - - - -<table style="width: 100%; border: solid #000 1px; border-bottom: solid #000 1px;" summary="list"> -<tr> - <td colspan="3"><div class="caption2nb">UNITED STATES DEPARTMENT OF AGRICULTURE</div></td> -</tr> -<tr> - <td class="tdl"><img src="images/page1_logo.png" width="91" height="80" alt="" /></td> - <td class="vtop caption2">BULLETIN No. 816<br /> - <span class="vsmall center">Contribution from the Bureau of Plant Industry<br /> - WM. A. TAYLOR, Chief</span></td> - <td><img src="images/page1_logo.png" width="91" height="80" alt="" /></td> -</tr> -</table> - -<table style="width: 100%; border-top: solid #000 1px; border-bottom: solid #000 1px;" summary="list"> -<tr> - <td class="tdl" style="width: 8em;">Washington, D. C.</td> - <td class="center"> ▼ </td> - <td class="tdr" style="width: 8em;">January 19, 1920</td> -</tr> -</table> - - - - -<h1>STREET TREES.</h1> - - -<h2>By <span class="smcap">F. L. Mulford</span>, <i>Horticulturist, Office of Horticultural and Pomological Investigations</i>.</h2> - - - -<hr class="chap" /> - - -<p class="caption2">CONTENTS</p> - -<div class="tblcont"> -<table style="width: 25em;" summary="ToC"> -<tr> - <td></td> - <td class="tdr smaller">Page</td> -</tr> -<tr> - <td class="tdl">Importance of Shade Trees</td> - <td class="tdr"><a href="#IMPORTANCE_OF_SHADE_TREES">1</a></td> -</tr> -<tr> - <td class="tdl">Public Control of Street Trees</td> - <td class="tdr"><a href="#PUBLIC_CONTROL_OF_STREET_TREES">6</a></td> -</tr> -<tr> - <td class="tdl">Planning for Trees on City Streets</td> - <td class="tdr"><a href="#PLANNING_FOR_TREES_ON_CITY_STREETS">8</a></td> -</tr> -<tr> - <td class="tdl">Spacing Trees</td> - <td class="tdr"><a href="#SPACING_TREES">9</a></td> -</tr> -<tr> - <td class="tdl">Conditions for Tree Growth</td> - <td class="tdr"><a href="#CONDITIONS_FOR_TREE_GROWTH">10</a></td> -</tr> -<tr> - <td class="tdl">Kinds of Trees Suitable for City Streets</td> - <td class="tdr"><a href="#KINDS_OF_TREES_SUITABLE_FOR_CITY_STREETS">14</a></td> -</tr> -<tr> - <td class="tdl"><span style="margin-left: 1em;">Qualities Necessary</span></td> - <td class="tdr"><a href="#QUALITIES_NECESSARY">14</a></td> -</tr> -<tr> - <td class="tdl"><span style="margin-left: 1em;">Trees for Different Regions</span></td> - <td class="tdr"><a href="#TREES_FOR_DIFFERENT_REGIONS">20</a></td> -</tr> -<tr> - <td class="tdl">Descriptions of Street Trees</td> - <td class="tdr"><a href="#DESCRIPTIONS_OF_STREET_TREES">20</a></td> -</tr> -<tr> - <td class="tdl">Culture of Street Trees</td> - <td class="tdr"><a href="#CULTURE_OF_STREET_TREES">43</a></td> -</tr> -<tr> - <td class="tdl"><span style="margin-left: 1em;">Selection of Individual Trees</span></td> - <td class="tdr"><a href="#SELECTION_OF_INDIVIDUAL_TREES">43</a></td> -</tr> -<tr> - <td class="tdl"><span style="margin-left: 1em;">Preparation of Holes</span></td> - <td class="tdr"><a href="#PREPARATION_OF_HOLES">44</a></td> -</tr> -<tr> - <td class="tdl"><span style="margin-left: 1em;">Planting</span></td> - <td class="tdr"><a href="#PLANTING">45</a></td> -</tr> -<tr> - <td class="tdl"><span style="margin-left: 1em;">Pruning</span></td> - <td class="tdr"><a href="#PRUNING">50</a></td> -</tr> -<tr> - <td class="tdl"><span style="margin-left: 1em;">Stakes and Guards</span></td> - <td class="tdr"><a href="#STAKES_AND_GUARDS">51</a></td> -</tr> -<tr> - <td class="tdl"><span style="margin-left: 1em;">Later Care</span></td> - <td class="tdr"><a href="#LATER_CARE">52</a></td> -</tr> -<tr> - <td class="tdl">Care of Mature Trees</td> - <td class="tdr"><a href="#CARE_OF_MATURE_TREES">53</a></td> -</tr> -<tr> - <td class="tdl"><span style="margin-left: 1em;">Pruning</span></td> - <td class="tdr"><a href="#PRUNING1">53</a></td> -</tr> -<tr> - <td class="tdl"><span style="margin-left: 1em;">Feeding</span></td> - <td class="tdr"><a href="#FEEDING">55</a></td> -</tr> -<tr> - <td class="tdl"><span style="margin-left: 1em;">Spraying</span></td> - <td class="tdr"><a href="#SPRAYING">55</a></td> -</tr> -</table> -</div> - - - -<h2><a name="IMPORTANCE_OF_SHADE_TREES" id="IMPORTANCE_OF_SHADE_TREES">IMPORTANCE OF SHADE TREES.</a></h2> - - -<p class="p0"><span class="dropcap">T</span>HE COMFORT to be derived from shade trees has long been -recognized. The early settlers of this country saved fine -trees about their homes, on the village greens, along the country -roads, and in the fields. Later, as villages grew, the householders -planted trees adjoining their properties, and the result has been -the beautiful elm-shaded villages of New England, the maple-shaded -towns of New York and the Ohio Valley, and the oak-shaded streets -of the Southeastern States. (<a href="#Fig_1">fig. 1.</a>)</p> - -<p>With time, the villages and towns became cities, and the woodlands -were largely destroyed. Conditions for tree growth were -less favorable in the cities, and nurseries had to be depended upon -for planting material. With these changed conditions the native -trees of a region became less dominant in the city planting and were -largely replaced by those trees listed in nursery catalogues which -took the fancy of each property owner along the street. (<a href="#Fig_2">fig. 2.</a>) -The quickest growing trees were considered first, and as some of these -made a big showing the first few years and were easily transplanted, -they have become the dominating trees in street planting from the -Atlantic to the Pacific and from the Great Lakes to the Gulf of -Mexico. (Figs. <a href="#Fig_2">2</a>, <a href="#Fig_10">10</a>, and <a href="#Fig_13">13</a>.) A few have planted better and more -lasting trees (figs. <a href="#Fig_1">1</a>, <a href="#Fig_3">3</a>, and <a href="#Fig_4">4</a>); but the tree growth on the streets -of the average town or city is ragged and unkempt in appearance, -while that of the suburb or small village is not much better unless -the planting has been done under municipal control and the plantings -on a street have been confined to a single kind of tree.</p> - -<p><span class="pagenum"><a name="Page_2" id="Page_2">« 2 »</a></span></p> - -<div class="fig_center" style="width: 485px;"><a id="Fig_1"></a> -<img src="images/fig1.png" width="485" height="340" alt="" /> -<div class="phnum">P15311HP</div> - -<div class="fig_caption"><span class="smcap">Fig. 1.</span>—An oak-shaded street in the South. -Willow oaks in Birmingham, Ala., in late summer.</div> -</div> - -<div class="fig_center" style="width: 484px;"><a id="Fig_2"></a> -<img src="images/fig2.png" width="484" height="326" alt="" /> -<div class="phnum">P18826HP</div> - -<div class="fig_caption"><span class="smcap">Fig. 2.</span>—A street with mixed plantings. The trees are of different kinds, some unsuited for the purpose, -planted at varying distances apart, according to the inclination of the property holders. A street in -Stockton, Calif., photographed in early summer.</div> -</div> - -<p><span class="pagenum"><a name="Page_3" id="Page_3">« 3 »</a></span></p> - -<div class="fig_center" style="width: 478px;"><a id="Fig_3"></a> -<img src="images/fig3.png" width="478" height="320" alt="" /> -<div class="phnum">P12515HP</div> - -<div class="fig_caption"><span class="smcap">Fig. 3.</span>—American elms on a city street in midsummer. All these trees were planted at one time at -uniform distances apart by the Commissioners of Washington, D. C.</div> -</div> - -<p>The advent of such civilizing agencies as the telegraph, the telephone, -the electric light, and the trolley car have added each its -share toward the mutilation or destruction of the good trees that -were in existence at the time of their coming. Faulty methods of -pruning also have caused much disfigurement and ruin. (Figs. <a href="#Fig_5">5</a> -and <a href="#Fig_21">21</a>.) To this mutilation has been added the unnecessary destruction -of many trees in centers of business (<a href="#Fig_6">fig. 6</a>), because they -excluded a little daylight, or made a store less prominent, or were -somewhat in the way of using the sidewalk for merchandise.</p> - -<p>In spite of all these troubles tree planting has continued because -people love trees, enjoy well-shaded streets, and are willing to make -efforts to get them. The trees on well-shaded streets are not only -pleasing, but also contribute toward the health of the community -by transpiring moisture into the atmosphere and by producing a -restful effect on eyes and nerves. Red, especially, is known to have -an exciting effect on human beings, and where city streets are well -<span class="pagenum"><a name="Page_4" id="Page_4">« 4 »</a></span>-shaded -it makes less prominent those colors that might otherwise -prevail and offend.</p> - -<div class="fig_center" style="width: 365px;"><a id="Fig_4"></a> -<img src="images/fig4.png" width="365" height="650" alt="" /> -<div class="fig_caption"><span class="smcap">Fig. 4.</span>—Trees 18 years old on adjacent streets: <i>A</i>, Pin oaks; <i>B</i>, ginkgos; <i>C</i>, Norway maples. Note the -differences in size.</div> -</div> - -<p><span class="pagenum"><a name="Page_5" id="Page_5">« 5 »</a></span></p> - -<p>Good shade is so appreciated that its presence adds a value to -adjoining properties. Real-estate men recognize this factor and plant -shade trees as early as practicable on land which they develop. -That the beauty of a city is improved by good street trees is becoming -recognized more and more and is finding expression in the -desire of garden clubs, civic improvement associations, and boards -of trade for information on this subject.</p> - -<div class="fig_right" style="width: 321px;"><a id="Fig_5"></a> -<img src="images/fig5.png" width="321" height="398" alt="" /> -<div class="phnum">P16692HP</div> - -<div class="fig_caption"><span class="smcap">Fig. 5.</span>—A tree mutilated by linemen. An otherwise beautiful red -oak in Louisville, Ky., as it appeared in midsummer.</div> -</div> - -<p>Success in planting street trees can be attained only by planning -and controlling the planting as a whole, by selecting the most suitable -varieties, by securing -trees in the best -condition and planting -them properly, and by -giving the necessary -later care.</p> - -<p>While towns were -small, conditions for -tree growth favorable, -and woodlands plenty, -so that native trees -were easily obtained -and started, the practice -of each householder -planting his -own trees as he saw -fit gave good results. -As towns became -larger and impervious -pavements took the -place of earth roads, -the conditions for tree -growth became more -severe and the results -from the individual -planting of trees less uniform. In large cities the conditions to be -met are so extreme that it has become practically impossible for the -average householder to grow street trees successfully, or to do so only -at excessive cost. Then, too, a lineman in a few minutes often undoes -what the individual has achieved with care and years of patient -waiting (see <a href="#Fig_5">fig. 5</a>). The trees and the lines are both needed by the -public, but when provided by individual initiative at private expense, -but trimmed for the benefit of electric lines by employees of corporations -intent on maintaining service at the least cost, the trees suffer -unduly.</p> - -<p><span class="pagenum"><a name="Page_6" id="Page_6">« 6 »</a></span></p> - -<p>In order to have good shade trees at a reasonable cost which -receive timely and efficient attention, with the effective control of -wire lines, the care of the trees needs to be vested in some adequate -authority.</p> - - - -<hr class="chap" /> -<h2><a name="PUBLIC_CONTROL_OF_STREET_TREES" id="PUBLIC_CONTROL_OF_STREET_TREES">PUBLIC CONTROL OF STREET TREES.</a></h2> - - -<p>Providing shade on city streets is as much a municipal function as -providing lights or sidewalks and should, therefore, be cared for by -public officials. All street trees should be directly under the care of -duly appointed officers, who should be responsible for their planting -and care, as well as for their pruning or removal. Negative control -by requiring permits for planting, pruning, and removal is little better -than no control.</p> - -<div class="fig_center" style="width: 480px;"><a id="Fig_6"></a> -<img src="images/fig6.png" width="480" height="331" alt="" /> -<div class="phnum">P16986HP</div> - -<div class="fig_caption"><span class="smcap">Fig. 6.</span>—A desert of asphalt in the business -center of a city having less than 100,000 population.</div> -</div> - -<p>The officials in charge should have the necessary authority and -should be required to initiate and carry forward planting and all -other needed work connected with the establishment and maintenance -of street trees. Probably the most satisfactory way of securing -supervision is through an unpaid commission of three or five members, -which in turn employs an executive officer. In a small place a commission -of three persons may be best, one being appointed every 2 -years for a 6-year term. In large places five members may be better, -and the ideal term would be 10 years. A compromise would be a -5-year term, a new member being appointed each year. The great -need of long-term appointees is that it takes two or three years for a -member of such a board or commission to see and realize the things -<span class="pagenum"><a name="Page_7" id="Page_7">« 7 »</a></span> -needed to be done and the policies that should be carried out. -Because it takes a long time to get results in growing street trees, the -policies should be as nearly continuous as possible and the terms of -the members long enough to insure a majority of experienced persons -on the board at all times.</p> - -<p>The method of appointing the commissioners is not so important -as that each shall be selected from the territory as a whole rather -than from a part of it. In some places where the term of service is -10 years, each one's successor is appointed by the remaining commissioners, -subject to confirmation by the court. Where this is done a -member is not permitted to succeed himself. In other places the -commission is appointed by the court; in others, it is elected by the -city legislative body or is appointed by the mayor subject to the -approval of the legislative body. The important point is to keep the -administration as nearly as possible on a purely business basis.</p> - -<p>A good board can accomplish nothing without liberal funds. There -are two methods of providing these: (1) By an appropriation from -the general tax levy and (2) by direct assessment against the properties, -collectible with the other taxes. If the funds are provided by -appropriation, a fixed minimum, expressed in millage of the tax -rate, should be provided in the organization of the commission. -This minimum should be such that a fair amount of maintenance work -can be done when no other funds are available. Councils that -appropriate money sometimes hamper boards by withholding appropriations. -Work of the nature of tree planting should not be permitted -to suffer or be lost by a year's neglect. The fund provided by -this minimum amount should not be so large that regular additional -appropriations will not be needed to carry on the work properly, as this -will give a desirable point of contact of the commission or board with -the ordinary channels of expressing public sentiment in the district -interested. The minimum appropriation mandatory should be sufficient -to prevent injury from lack of care of work already begun. A -period of minimum care and attention while a board and the people or -their representatives are coming to a new understanding of one -another's position is not necessarily a detriment, provided a reasonable -maintenance has been possible in the interim, but without such -care the results are ruinous and work would better not be started -than be undertaken with the possibility of such a period of neglect -occurring.</p> - -<p>It is probably desirable to assess the cost of tree planting against -the adjacent property owners at a proportional cost per front foot -and to provide for maintenance out of a general fund. Boulevards -and other unusual developments are sometimes maintained with -satisfactory results by regular assessments against the abutting -properties.</p> - -<p><span class="pagenum"><a name="Page_8" id="Page_8">« 8 »</a></span></p> - -<p>After a proper governing board is provided, the securing of a -competent executive is a matter of ordinary business procedure. -It is usually desirable that he shall be not only a good executive but -also a man with a knowledge of trees and trained in their care, so -that he may be a competent adviser of the board as well as its -executive.</p> - -<div class="fig_center" style="width: 477px;"><a id="Fig_7"></a> -<img src="images/fig7.png" width="477" height="310" alt="" /> -<div class="phnum">P18857HP</div> - -<div class="fig_caption"><span class="smcap">Fig. 7.</span>—Increased attractiveness due to trees on a city street, as shown by contrasting the two sides -of the thoroughfare. If trees like red oaks, American elms, or the Eucalyptus in the distance had -been used, the effect on this wide street would have been comparable to <a href="#Fig_3">figure 3</a>. The trees in the -left foreground are umbrella trees. Merced, Calif.; midsummer.</div> -</div> - - - -<hr class="chap" /> -<h2><a name="PLANNING_FOR_TREES_ON_CITY_STREETS" id="PLANNING_FOR_TREES_ON_CITY_STREETS">PLANNING FOR TREES ON CITY STREETS.</a></h2> - - -<p>With the help of one who knows trees and the local conditions to -be met, the town should be studied and a suitable kind of tree selected -for each street or for a large portion of a street (figs. <a href="#Fig_1">1</a> and <a href="#Fig_3">3</a>), and as -conditions warrant the plan should be carried out as outlined. Mixed -plantings of different sorts of trees (figs. <a href="#Fig_2">2</a> and <a href="#Fig_7">7</a>) are not as pleasing -and effective as the use of a single species for considerable distances. -The use of only one or two kinds for a whole town is likely to be -monotonous, and it is also undesirable because the variety most used -may become subject to serious disease or insect attacks. The -species and varieties of trees suitable for city planting are few enough, -if all are used, so an endeavor should be made to include as many -different kinds as practicable, assigning one variety for a long stretch -of street unless there is a marked change in its character, in which -case a change of trees would be warranted.</p> - -<p>Where trees are already on a street, the problem of planning for -the future is frequently much complicated, especially if there are -several kinds in good condition. Where there is but one good kind, -<span class="pagenum"><a name="Page_9" id="Page_9">« 9 »</a></span> -gaps can be replanted with young trees of that sort. If there are -poor trees of a good variety or trees of a poor or short-lived variety -it would be advisable to remove these and do all the replanting at -one time, so as to have the trees on the street as nearly uniform as -possible. Where there are several good varieties in good condition -the sensible thing is to care for the trees that are there and then, after -careful study, decide on one variety for all future plantings on that -street.</p> - -<div class="fig_center" style="width: 477px;"><a id="Fig_8"></a> -<img src="images/fig8.png" width="477" height="503" alt="" /> -<div class="phnum">P14631HP</div> - -<div class="fig_caption"><span class="smcap">Fig. 8.</span>—Trees 20 feet apart that should be at least 60 feet apart. Sycamores in Washington, D. C., as -they appear in late winter.></div> -</div> - - - -<hr class="chap" /> -<h2><a name="SPACING_TREES" id="SPACING_TREES">SPACING TREES.</a></h2> - - -<p>A common fault in all street planting is to put the trees too near -together. (<a href="#Fig_8">fig. 8.</a>) This is more evident where the work has -been done by the abutting property owners than by municipalities.</p> - -<p>After trees are started and have attained some size it is extremely -difficult to get them removed, even where the good of the remaining -trees demands it. The removal of a fairly good tree merely because<span class="pagenum"><a name="Page_10" id="Page_10">« 10 »</a></span> -it is short lived in order to make room for a good one that will be -permanent does not appeal to the average citizen. Where trees -which have been planted by the property holder come under city -control a strong feeling of proprietorship still remains, which is -outraged by the suggestion of the removal of even poor trees. Where -all the work is under city control good work is often hampered by a -strong public sentiment against the removal of trees, even though they -are poor or crowding.</p> - -<p>Because of this difficulty it is extremely important that young -trees be planted farther apart than at that time seems reasonable. -If they are planted as far apart as is proper for mature trees the -distance will be so great as to make planting seem a joke. If they -are planted half the distance apart they should be when mature, -good results would follow if the intermediate trees were removed -when they nearly touch those to be left. As the intermediate -trees would probably not be removed, or not until too late for the -good of the remaining ones, planting had better be sufficiently -far apart in the beginning to avoid the necessity of later removals. -In the beginning the trees will be too far apart and when mature -too close together, but it seems to be the alternative imposed by a -misguided public opinion.</p> - -<p>There is scarcely a community that would permit the removal of -interplanted trees from a street of fine elms, oaks, or other worthy -varieties without a protest that would be the almost sure political -death of the administrative authorities responsible, no matter how -great the need or how much expert support they might have. If -short-lived intermediate trees were used they would not be likely to -be taken out before they died, and they probably would not die before -they had irreparably injured the permanent trees. The removal of -surplus or interplanted trees can be made with least shock to the -community by gradually narrowing the tree tops by severe pruning -from year to year on the sides next the permanent trees until finally -they are so narrow they may be removed and leave only small -openings between the permanent trees. Even this method will not -materially lessen the public protest at the final removal.</p> - -<p>A common practice is to set street trees 35 feet apart. If it were -practicable to remove one-half the trees at the proper time this would -be a good distance, but in the eastern half of the United States and -on the Pacific slope 50 feet apart is close enough for most varieties, -and for the larger growing trees 60 to 70 feet would be better.</p> - - - -<hr class="chap" /> -<h2><a name="CONDITIONS_FOR_TREE_GROWTH" id="CONDITIONS_FOR_TREE_GROWTH">CONDITIONS FOR TREE GROWTH.</a></h2> - - -<p>In order to grow, trees must have a soil of suitable texture, in -proper mechanical condition, that contains sufficient available mineral -elements and plenty of organic matter, and, last but not least, a constant -supply of moisture and air. In addition to these there must -<span class="pagenum"><a name="Page_11" id="Page_11">« 11 »</a></span> -be in active growth in the soil many forms of organic life that are in -various ways preparing the material in the soil for the use of the -larger plants. Not only must these things be present, but others -that are deleterious must be absent, whether the substance is hurtful -in itself or whether it is an excess of one that is otherwise beneficial.</p> - -<p>Above the soil three things must be present—air, sunlight, and -moisture—and, as in the soil, harmful things must be absent in order -to have success. Among the deleterious substances are sulphur and -other fumes and soot and other products from incomplete combustion.</p> - -<div class="fig_center" style="width: 471px;"><a id="Fig_9"></a> -<img src="images/fig9.png" width="471" height="349" alt="" /> -<div class="phnum">P14633HP</div> - -<div class="fig_caption"><span class="smcap">Fig. 9.</span>—The irregularity in the size of the trees shown is due to a part of the first planting having been -killed by illuminating gas from defective pipes. Norway maples as seen in Washington, D. C., in -late winter.></div> -</div> - -<p>Some of the more obvious things with which a city tree has to -contend are: Water-tight pavements, both on the sidewalk and -street, that prevent the admission of air and water; the removal of -the topsoil in street grading, thus forcing the tree to exist on the -good soil provided in the hole; careless digging near the tree for gas, -water, and electric service, and especially for the placing of curb-stones; -the saturation of the soil with illuminating or sewer gas from -defective pipes (<a href="#Fig_9">fig. 9</a>); the pouring of salt water from ice-cream -freezers into gutters, where it may find its way into the soil near tree -roots; the gnawing of the trunks by horses; and the cutting of the -tops by linemen and tree trimmers.</p> - -<p>Because of the uncongenial conditions for the growth of trees on -city streets comparatively few kinds are satisfactory for such use. -<span class="pagenum"><a name="Page_12" id="Page_12">« 12 »</a></span> -Among those available are some that will grow under extremely -trying conditions. Kinds can be found that will thrive wherever it -is suitable for human beings to live. If it is impossible to grow trees -on a street, as a health measure that street should be closed for -human use until conditions are so improved that it will support -trees.</p> - -<div class="fig_center" style="width: 477px;"><a id="Fig_10"></a> -<img src="images/fig10.png" width="477" height="342" alt="" /> -<div class="phnum">P15298HP</div> - -<div class="fig_caption"><span class="smcap">Fig. 10.</span>—A business center relieved by a parking with Carolina poplars. -Macon, Ga.; late summer.</div> -</div> - -<p>More kinds will thrive under suburban conditions where only a -small portion of the roadway is covered by an impervious coating, where -the parking spaces are liberal, and where the street is lined with -open lawns than under the conditions in a city, where the street is -covered with a water and air proof coating and the sidewalks with -an impervious material, where parking spaces are limited, and where -adjoining lawn areas are small or lacking. By a careful selection of -kinds, all conditions in a city can be met. In some places bad conditions -could have been improved greatly by a little forethought; in -others, such conditions can be bettered. These details, like many -other matters connected with city planning, have been ignored, but -should be considered immediately, especially by villages and small -cities. <a href="#Fig_6">Figure 6</a> shows how an opportunity for creating a beauty -spot has been lost sight of, while <a href="#Fig_10">figure 10</a> shows how a city has -utilized less ground to increase the comfort and attractiveness of its -business center.</p> - -<p><span class="pagenum"><a name="Page_13" id="Page_13">« 13 »</a></span></p> - -<div class="fig_center" style="width: 472px;"><a id="Fig_11"></a> -<img src="images/fig11.png" width="472" height="274" alt="" /> -<div class="phnum">P15278HP</div> - -<div class="fig_caption"><span class="smcap">Fig. 11.</span>—A street well proportioned in width of roadway, sidewalk, and parkings, with willow oaks -on the left, American elms on the right, and young Carolina poplars near the roadway that should -be removed. Columbus, Ga.; midsummer.</div> -</div> - -<div class="fig_center" style="width: 475px;"><a id="Fig_12"></a> -<img src="images/fig12.png" width="475" height="260" alt="" /> -<div class="phnum">P14359HP</div> - -<div class="fig_caption"><span class="smcap">Fig. 12.</span>—A street with too much pavement and too little parking space. Carolina poplars in Baltimore, -Md., in midautumn.</div> -</div> - -<p>A common mistake in ambitious young cities and many old ones -is to pave more of the width of the street for traffic purposes than, is -likely ever to be needed. By reducing the roadway and throwing the -remainder into liberal parking spaces much is added to the attractiveness -and comfort of a city. A contrast in the two methods of treatment -is illustrated in figures <a href="#Fig_11">11</a> and <a href="#Fig_12">12</a>. The recommendation that -the roadway prepared for travel be made narrow is not to be interpreted -as a reason for lessening the area dedicated to the public use; -in fact, in most cities, especially in the northeastern quarter of the -United States, too little space has been reserved from houseline to -houseline (<a href="#Fig_13">fig. 13</a>). By reserving more room between the houses and -<span class="pagenum"><a name="Page_14" id="Page_14">« 14 »</a></span> -the street for use as lawns and gardens the conditions would be made -more livable, opportunity would be offered for widening the public -way without prohibitive expense if traffic or business demanded it, -and the growing of street trees would cease to be a serious problem.</p> - -<div class="fig_center" style="width: 479px;"><a id="Fig_13"></a> -<img src="images/fig13.png" width="479" height="308" alt="" /> -<div class="phnum">P16842HP</div> - -<div class="fig_caption"><span class="smcap">Fig. 13.</span>—A street with too little room from houseline to houseline. Note the more attractive appearance -of the side with trees. Norway and silver maples in Frederick, Md., in midsummer.</div> -</div> - - - -<hr class="chap" /> -<h2><a name="KINDS_OF_TREES_SUITABLE_FOR_CITY_STREETS" id="KINDS_OF_TREES_SUITABLE_FOR_CITY_STREETS">KINDS OF TREES SUITABLE FOR CITY STREETS.</a></h2> - - -<h3><a name="QUALITIES_NECESSARY"></a>QUALITIES NECESSARY.</h3> - -<p>Compared with the whole number of trees used for ornamental -planting, the number of kinds suitable for street planting is very -small. For use under city conditions a tree must be adapted to the -climate and to the soil upon which it is to be grown. It must have -healthy foliage that withstands dust and smoke and a root system -not easily affected by unusual soil conditions, by restricted feeding -areas, or by root pruning when street improvements are made. The -top should be in proportion to the width of the street upon which it -is used, and it should be rather high headed or easily trained to that -form and of open growth without being too spreading or sprawling.</p> - -<p>Of minor consideration is the character of the foliage masses, -whether dark or light, heavy and somber or open and airy, and also -whether they have vivid autumn colorings. Only in the most southern -parts of the country and in western California should evergreen -trees be considered for street planting, and then only the broad-leaved -evergreens, such as magnolias and live oaks. In the North -the lack of sunshine during the short cloudy days of winter makes it -desirable to admit all the light possible. Even in the South the -question of sunshine should be considered when selecting varieties.</p> - -<p><span class="pagenum"><a name="Page_15" id="Page_15">« 15 »</a></span></p> - -<div class="fig_right" style="width: 321px;"><a id="Fig_14"></a> -<img src="images/fig14.png" width="321" height="389" alt="" /> -<div class="phnum">P125365HP</div> - -<div class="fig_caption"><span class="smcap">Fig. 14.</span>—Narrow upright trees (Lombardy poplars) on a Barrow -Conditions, it is better street. Washington, D. C.; midsummer.</div> -</div> - -<p>Narrow streets should be planted with columnar trees (<a href="#Fig_14">fig. 14</a>) -or sometimes with small trees. Broad streets may be planted with -spreading trees (figs. <a href="#Fig_3">3</a> -and <a href="#Fig_16">16</a>), or, if provided -with a central -parking space, with -moderate-sized trees -in the center and on -the sides, or with trees -on the sides suited to -the space and formal -trees in the center. -(<a href="#Fig_15">fig. 15.</a>)</p> - -<div class="fig_left" style="width: 318px;"><a id="Fig_15"></a> -<img src="images/fig15.png" width="318" height="263" alt="" /> -<div class="phnum">P18856HP</div> - -<div class="fig_caption"><span class="smcap">Fig. 15.</span>—Formal trees in a central parking, but appropriate trees -wanting on the sides of the street. Canary Island date palms in -Merced, Calif.; midsummer.</div> -</div> - -<p>As a rule, trees native -to the locality -that have been successfully -grown in -other cities should be -given the preference. -When a choice must -be made between untried -native trees and -those tested in a city -or town under different -soil or climatic -to give the native trees -the first trial. There -are many native trees -that are promising -which have not been -planted on a sufficient -scale or under sufficiently -varied conditions -to demonstrate -their real value for -street planting over -any considerable area. -Many of the trees mentioned -in this bulletin -may prove valuable -far beyond the areas -for which they are suggested. -The burr oak, -the swamp white oak, the scarlet oak, the chestnut oak, the white -oak, the sour gum, and others may be found on further trial to be as -<span class="pagenum"><a name="Page_16" id="Page_16">« 16 »</a></span> -valuable as those already demonstrated to be valuable over large -areas. Those mentioned have all been tested in a small way.</p> - -<p>Caution should be used in selecting trees with conspicuous flowers -and those with edible fruits or nuts, as in many parts of the country -such trees are badly mutilated by the public. Even horse-chestnuts, -although the nuts are not edible, are often broken by boys clubbing -the trees. That public opinion can prevent such vandalism is in evidence -all along the Pacific coast and at a few places in the East. -Every effort should be made to create a sentiment that will protect -these attractive additions to street adornment, but where the sentiment -does not exist it is better to avoid the planting of such trees -except in a limited way.</p> - -<div class="fig_center" style="width: 477px;"><a id="Fig_16"></a> -<img src="images/fig16.png" width="477" height="304" alt="" /> -<div class="phnum">P15394HP</div> - -<div class="fig_caption"><span class="smcap">Fig. 16.</span>—Live oaks, the handsomest southern street tree for broad street: -Biloxi, Miss.; late summer.</div> -</div> - -<p>Besides the native trees there are many introduced trees that have -proved valuable and many more that are worthy of trial.<a name="FNanchor_1" id="FNanchor_1"></a><a href="#Footnote_1" class="fnanchor">[1]</a> A fair -trial of promising introduced trees should be made, and the native -kinds should be thoroughly tested.</p> - -<div class="footnote"> - -<p><a name="Footnote_1" id="Footnote_1"></a><a href="#FNanchor_1"><span class="label">[1]</span></a> As examples of this are a number of new elms such as <i>Ulmus pumila</i> and <i>Ulmus densa</i>, besides lindens, -poplars, and <i>Koelreuteria paniculata</i>, while <i>Pistacia chinensis</i> is suitable for warm regions. The Office -of Foreign Seed and Plant Introduction of the United States Department of Agriculture will be glad at -any time to suggest new trees that are promising for any region.</p></div> - - -<h3><a id="TREES_FOR_DIFFERENT_REGIONS"></a>TREES FOR DIFFERENT REGIONS.</h3> - -<p>To simplify the discussion of kinds of street trees likely to prove -satisfactory, the United States has been arbitrarily divided into the -regions shown in <a href="#Fig_17">figure 17</a>. An endeavor has been made to make -each division cover an area having similar growing conditions, so that -the trees suggested will be likely to thrive in all its parts. A discussion -<span class="pagenum"><a name="Page_17" id="Page_17">« 17 »</a></span> -of the strong and weak points of the different kinds will be -found with the description of the kinds farther on in this bulletin.</p> - -<div class="blockqtsm"> - -<p><i>Region 1.</i>—Region 1 comprises the mild humid portion of the northern Pacific coast -east to the Cascade Mountains, including the western third of Washington and Oregon -and a portion of northern California. The trees native to western Europe are adapted -to this region, as the climatic conditions are quite comparable. Most of our American -trees also succeed here.</p> - -<p>Some of the desirable varieties for street planting in region 1 are the Oregon, Norway, -sycamore, and sugar maples; California walnut; tulip; European linden; basswood; -sycamore; London plane; white and European ashes; English and American elms; -English, red, and pin oaks; ginkgo; and the black locust.</p></div> - -<div class="fig_center" style="width: 476px;"><a id="Fig_17"></a> -<img src="images/fig17.png" width="476" height="323" alt="" /> -<div class="fig_caption"><span class="smcap">Fig. 17.</span>—Outline map of the United States, showing the regions within which essentially similar conditions -for tree growth exist.</div> -</div> - -<div class="blockqtsm"> - -<p><i>Region 2.</i>—Region 2 is that portion of California lying between the Sacramento and -San Joaquin Valleys and the Pacific Ocean. Many varieties of trees will succeed -here if given water. Because of the lack of water, unless specially irrigated the more -drought-resistant species should be used.</p> - -<p>Among the deciduous trees useful for this region are the London plane; the California -and common sycamore; English, Huntingdon, and American elms; Oregon, -Norway, sycamore, and English maples; white, green, and European ashes; red, -English, and pin oaks; European linden; basswood; California walnut; honey and -black locusts; horse-chestnut; Albizzia; and the Japanese varnish tree, or Sterculia.</p> - -<p>Evergreen trees which will probably be successful in region 2 are the Eucalyptus<a name="FNanchor_2" id="FNanchor_2"></a><a href="#Footnote_2" class="fnanchor">[2]</a> -in variety, acacias, rubber, magnolia, California live oak, Victorian and poplar-leaved -bottle trees, and in the southern portions the California pepper, silk oak, and jacaranda. -Palms are much planted, but they do not make good street trees except where -a formal effect instead of shade is desired.</p></div> - -<div class="footnote"> - -<p><a name="Footnote_2" id="Footnote_2"></a><a href="#FNanchor_2"><span class="label">[2]</span></a> Some cities have ordinances against the planting of certain trees because their roots sometimes obstruct -sewers. Among these trees are the Eucalyptus in California and some of the poplars in several -of the States.</p></div> - - - -<p><span class="pagenum"><a name="Page_18" id="Page_18">« 18 »</a></span></p> - -<div class="blockqtsm"> - -<p><i>Region 3.</i>—Region 3 comprises the Sacramento and San Joaquin Valleys.</p> - -<p>The deciduous trees for this region are the California walnut; London plane; California -and common sycamores; Oregon, Norway, and sycamore maples; white, -European, and green ashes; red, English, valley, and pin oaks; European linden; -basswood; English and Huntingdon elms; honey locust; and horse-chestnut. Chinaberries -and Texas umbrellas are much planted in these valleys, but are not good -street trees. Olives and palms are suitable only for formal effects, while eucalypti -are satisfactory but are liable to make trouble with defective sewers. Acacias grow -especially well in this region except in the extreme north.</p> - -<p><i>Region 4.</i>—Region 4 includes the country from the Sacramento and San Joaquin -Valleys to the crest of the Sierra Nevada Mountains. It varies in elevation and -correspondingly in temperature and the amount of available moisture.</p> - -<p>Where there is sufficient moisture, the deciduous trees recommended for region 3, -except the valley oak and possibly the California sycamore, may be used. Where -there is less moisture the thornless honey locust, black locust, green ash, hackberry, -poplars, ash-leaved maple, and the American elm if it can be watered the first few -years may be planted. In the warmer sections the chinaberry and Texas umbrella -may be used.</p> - -<p><i>Region 5.</i>—Region 5 comprises the hot semiarid country of southern California and -southwestern Arizona which is dependent on irrigation.</p> - -<p>The best deciduous trees for this region are those suggested for the drier portions of -region 4. With ample irrigation the deciduous trees recommended for region 3 might -grow.</p> - -<p>Among the evergreens the Texas palmetto, Parkinsonia, and the Washingtonia -and some other palms can be used where other trees do not succeed. The red and -desert gums may be used also in the drier regions. With ample irrigation the evergreens -suggested for region 2 should succeed.</p> - -<p><i>Region 6.</i>—Region 6 comprises the intermountain section and extends from the -crest of the Cascade and Sierra Nevada Mountains eastward to the eastern base of the -Rocky Mountains. The region includes great variations in growing conditions, -often in very short distances. As a whole it is semiarid, and in most places trees -can hardly be expected to thrive without more or less irrigation, although in some of -the mountain valleys and on some of the mountain slopes almost ideal conditions for -tree growth exist.</p> - -<p>In the drier parts of the region only those deciduous trees that are weeds under more -congenial conditions can be grown. Those that can be planted with the greatest -hope of success are the thornless honey locust, black locust, green ash, hackberry, -and where the others do not succeed, the poplars and ash-leaved maple. If it can be -watered for a few years the American elm usually can be grown, and in the southern -half of the region the Mississippi hackberry will probably succeed. Near the southern -border, on lower elevations, the chinaberry and Texas umbrella can also be planted. -In the locations most favored naturally or where irrigation is possible, the trees -suggested for region 9 can be used.</p> - -<p>Evergreens that may be used for the drier portions of the southern part of region 6 -are the Parkinsonia and the Texas palmetto.</p> - -<p>Native trees may be found that will prove of greater value for limited areas than any -suggested. Cities and towns contemplating street tree planting would do well to -consult the nearest State agricultural experiment station or the United States Department -of Agriculture if it is thought possible that something better has been found -than the trees suggested.</p> - -<p><i>Region 7.</i>—Region 7 is the northern part of the Great Plains area from the foot of the -Rocky Mountains at about the 5,000-foot contour line east to the ninety-eighth meridian. -It is rather uniform in general conditions, the character of soil having no wide -divergence and the elevation increasing gradually from south to north and east to west. -<span class="pagenum"><a name="Page_19" id="Page_19">« 19 »</a></span> -The rainfall gradually increases from west to east until at about the ninety-eighth -meridian the conditions are more favorable for tree growth.</p> - -<p>The trees to be relied on are the thornless honey locust, common hackberry, black -locust, green ash, ash-leaved maple, the poplars, the Chinese elm, and the American elm -if it can be watered the first few years after transplanting. The mossy-cup oak is -another tree worth testing in a small way, as it is native a little east of the ninety-eighth -meridian. The basswood and Norway maple would probably succeed if -supplied with plenty of water.</p> - -<p><i>Region 8.</i>—Region 8 is the southern part of the Great Plains.</p> - -<p>In addition to the deciduous trees recommended for the northern Great Plains -(region 7) the Mississippi hackberry, Texas umbrella, and chinaberry may be successfully -grown.</p> - -<p>Evergreen trees that may be used in region 8 are the Texas palmetto and Parkinsonia.</p> - -<p><i>Region 9.</i>—Region 9 is the upper Mississippi Valley, including the area from that -already considered to Lake Michigan and south to southern Kansas. It is more -favorable to tree growth than regions 6 and 7.</p> - -<p>Trees which will succeed here are the American elm; red, pin, mossy-cup, and -other native oaks; white ash; sycamore; basswood; and Norway and sugar maples.</p> - -<p><i>Region 10.</i>—Region 10 includes the northeastern part of the country from eastern -Illinois to the Atlantic Ocean, and extends southward through the Appalachian -Mountains. It is most favorable for tree growth.</p> - -<p>The best trees for street planting in region 10 are the red and pin oaks, London -plane, sycamore, the staminate form of the ginkgo, basswood, tulip, Norway maple, -white ash, thornless honey locust, American elm, and in the southern portion of the -region on light land the sweet gum. The red and sugar maples are among the best -trees for suburban conditions. The hackberry will grow, but should be discarded -in favor of better varieties. The mossy-cup and chestnut oaks are worthy of trial -on gravelly soils in the suburbs.</p> - -<p><i>Region 11.</i>—Region 11 includes the lower Mississippi Valley and the country east -of the southern Appalachian Mountains, extending from the light lands near the -South Atlantic and Gulf coasts to the northern limits of the distinctively southern -flora.</p> - -<p>The typical street trees of this region are the willow oaks (<a href="#Fig_1">fig. 1</a>) and water oaks, -the former a valuable street tree, the latter good when young but comparatively -short lived, with no advantages over the willow oak. Other good trees are the red, -Spanish, laurel, Darlington, and pin oaks, tulip, sweet gum, American elm, red and -Norway maples, and the ginkgo.</p> - -<p><i>Region 12.</i>—Region 12 is the land near the coast from Wilmington, N. C., to the -Mexican border, exclusive of the southern part of Florida.</p> - -<p>Good deciduous trees for this region are the willow, laurel, Darlington, and Spanish -oaks, tulip, sweet gum, sycamore, London plane, American elm, and the staminate -form of the ginkgo. The honey locust, red or scarlet maple, Norway maple, -and the hackberries are not so good.</p> - -<p>The live oak is the characteristic tree of region 12 (<a href="#Fig_16">fig. 16</a>) and is the pride of the -cities that have used it. Even though an evergreen, it is an excellent street tree, -as it is large, spreading, and open. The palmetto and palms thrive and may be -used for producing formal effects. The evergreen magnolia is a good broad-leaved -evergreen.</p> - -<p><i>Region 13.</i>—Region 13 consists of the southern part of Florida. The deciduous -trees suitable for this section are the willow, Spanish, and southern red oaks; American -elm; Mississippi hackberry; and in the southern half of the region the -Poinciana.</p> - -<p>Evergreen trees are better suited to region 13 than to, any other portion of the -United States except possibly southern California. Among the best are the live and -<span class="pagenum"><a name="Page_20" id="Page_20">« 20 »</a></span> -laurel oaks, evergreen magnolia, camphor, rubber, silk oak, or grevillea, and casuarina. -Eucalypti are planted to some extent in Florida, but the climate is such that -only on the drier grounds of the interior are they likely to succeed, and even there -they are not to be compared with other excellent species of trees that may be cultivated -successfully.</p></div> - - -<h3><a id="TREES_FOR_SPECIAL_PURPOSES"></a>TREES FOR SPECIAL PURPOSES.</h3> - -<p>In the heart of a city, where the greatest difficulty is experienced -in getting trees to grow, the ailanthus will probably thrive when -nearly all other kinds fail. The sycamore and the London plane -are also good for such places. The Carolina poplar will frequently -grow under these conditions, and its use may sometimes be -warranted.</p> - -<p>For very narrow streets the Lombardy poplar is the best tree. -(<a href="#Fig_14">fig. 14.</a>) Trees suitable for use within the reach of ocean spray or -on sandy lands near the coast are the red oak and the red or scarlet -maple south to Charleston, S. C., while the sweet gum and the live -oak are equally good from Norfolk southward and along the Gulf of -Mexico. The red oak, sweet gum, red maple, and eastern live oak -are all grown successfully along the Pacific Ocean, while the California -live oak can be used from San Francisco southward. The trees -that endure the most alkali appear to be the bladder-nut tree,<a name="FNanchor_3" id="FNanchor_3"></a><a href="#Footnote_3" class="fnanchor">[3]</a> -London plane, peppermint gum,<a name="FNanchor_4" id="FNanchor_4"></a><a href="#Footnote_4" class="fnanchor">[4]</a> blue gum,<a name="FNanchor_5" id="FNanchor_5"></a><a href="#Footnote_5" class="fnanchor">[5]</a> the Washingtonia and -other hardy fan palms, Canary Island date palm, the camphor -tree, and <i>Acacia cyclops</i> and <i>Acacia retinodes</i>. Only the first two -withstand severe freezing weather. The red oak and the red maple -are worth testing for these conditions.</p> - -<div class="footnote"> - -<p><a name="Footnote_3" id="Footnote_3"></a><a href="#FNanchor_3"><span class="label">[3]</span></a> <i>Koelreuteria paniculata</i>.</p></div> - -<div class="footnote"> - -<p><a name="Footnote_4" id="Footnote_4"></a><a href="#FNanchor_4"><span class="label">[4]</span></a> <i>Eucalyptus amygdalina</i> Labill.</p></div> - -<div class="footnote"> - -<p><a name="Footnote_5" id="Footnote_5"></a><a href="#FNanchor_5"><span class="label">[5]</span></a> <i>Eucalyptus amygdalina angustifolia</i>.</p></div> - - - - -<h2><a name="DESCRIPTIONS_OF_STREET_TREES" id="DESCRIPTIONS_OF_STREET_TREES">DESCRIPTIONS OF STREET TREES.</a></h2> - - -<h3><a id="ACACIA"></a>ACACIA.</h3> - -<p>The acacias, or wattles, are a large group mostly of small trees -with showy yellow flowers. Although much used in California, many -of them are too small to make satisfactory shade trees, and because -of shallow rooting they are injurious to sidewalks. They also stump-sprout -badly. They thrive in regions 2 and 3 and in restricted -portions of regions 1 and 5.</p> - -<p>The Australian blackwood,<a name="FNanchor_6" id="FNanchor_6"></a><a href="#Footnote_6" class="fnanchor">[6]</a> blackwood acacia, or wattle, is a -strong, upright tree, growing to a height of 75 feet and forming a -well-shaped head. It is badly affected by citrus scale, and on this -account its planting is sometimes prohibited.</p> - -<div class="footnote"> - -<p><a name="Footnote_6" id="Footnote_6"></a><a href="#FNanchor_6"><span class="label">[6]</span></a> <i>Acacia melanoxylon</i> R. Br.</p></div> - -<p>The black wattle<a name="FNanchor_7" id="FNanchor_7"></a><a href="#Footnote_7" class="fnanchor">[7]</a> is a strong-growing round-headed tree that -reaches a height of 40 feet and has dark-green leaves.</p> - -<div class="footnote"> - -<p><a name="Footnote_7" id="Footnote_7"></a><a href="#FNanchor_7"><span class="label">[7]</span></a> <i>Acacia decurrens mollis</i> Lindl.</p></div> - -<p>The green wattle<a name="FNanchor_8" id="FNanchor_8"></a><a href="#Footnote_8" class="fnanchor">[8]</a> is a rapid-growing tree, reaching a height of -60 feet and forming a round head with finely cut leaves.</p> - -<div class="footnote"> - -<p><a name="Footnote_8" id="Footnote_8"></a><a href="#FNanchor_8"><span class="label">[8]</span></a> <i>Acacia decurrens</i> Willd.</p></div> -<p><span class="pagenum"><a name="Page_21" id="Page_21">« 21 »</a></span></p> -<p>The silver wattle<a name="FNanchor_9" id="FNanchor_9"></a><a href="#Footnote_9" class="fnanchor">[9]</a> is much like the black wattle except that its -leaves and young branches are covered with a whitish down.</p> - -<div class="footnote"> - -<p><a name="Footnote_9" id="Footnote_9"></a><a href="#FNanchor_9"><span class="label">[9]</span></a> <i>Acacia decurrens dealbata</i> F. Muell.</p></div> - - -<h3><a id="AILANTHUS"></a>AILANTHUS.</h3> - -<p>The ailanthus,<a name="FNanchor_10" id="FNanchor_10"></a><a href="#Footnote_10" class="fnanchor">[10]</a> or tree of heaven, is a tall, broad, handsome tree -that is especially valuable in the heart of closely built or smoky -cities. The staminate and pistillate flowers are borne on separate -trees. Only the pistillate trees should be used, as the odor of the -blossoms of the staminate ones is very objectionable for about 10 -days in late spring. These may be produced by grafting from pistillate -trees or by propagating from suckers or root cuttings from such -trees if they have not been grafted. The ailanthus may not succeed -in regions 5 and 13.</p> - -<div class="footnote"> - -<p><a name="Footnote_10" id="Footnote_10"></a><a href="#FNanchor_10"><span class="label">[10]</span></a> <i>Ailanthus altissima</i> (Mill.) Swingle (<i>A. glandulosa</i> Desf.).</p></div> - - -<h3><a id="ASH"></a>ASH.</h3> - -<p>There are three kinds of ash trees that are useful for street planting.</p> - -<p>The white ash<a name="FNanchor_11" id="FNanchor_11"></a><a href="#Footnote_11" class="fnanchor">[11]</a> is a large oval-headed tree, reasonably satisfactory -on rich lands in regions 1, 2, 3, 4, 9, 10, 11, and 12, but it is better -adapted to suburban than urban conditions.</p> - -<div class="footnote"> - -<p><a name="Footnote_11" id="Footnote_11"></a><a href="#FNanchor_11"><span class="label">[11]</span></a> <i>Fraxinus americana</i> L.</p></div> - -<p>The green ash<a name="FNanchor_12" id="FNanchor_12"></a><a href="#Footnote_12" class="fnanchor">[12]</a> is one of the few successful trees in regions 6, 7, -and 8 and may succeed in region 5. It grows well throughout the -remainder of the United States, but is of less value than other trees -there. It is much smaller than the white ash, with a broad round top.</p> - -<div class="footnote"> - -<p><a name="Footnote_12" id="Footnote_12"></a><a href="#FNanchor_12"><span class="label">[12]</span></a> <i>Fraxinus lanceolata</i> Borck.</p></div> - -<p>The European ash<a name="FNanchor_13" id="FNanchor_13"></a><a href="#Footnote_13" class="fnanchor">[13]</a> is a large, handsome, round-headed tree suited -to regions 1, 2, 3, and 4.</p> - -<div class="footnote"> - -<p><a name="Footnote_13" id="Footnote_13"></a><a href="#FNanchor_13"><span class="label">[13]</span></a> <i>Fraxinus excelsior</i> L.</p></div> - - -<h3><a id="CAMPHOR"></a>CAMPHOR.</h3> - -<p>The camphor tree<a name="FNanchor_14" id="FNanchor_14"></a><a href="#Footnote_14" class="fnanchor">[14]</a> is a large, handsome, oval-headed evergreen -that will succeed in the southern half of region 2, in regions 3, 5, and 13, -and in the warmer parts of region 12. It will endure more frost than -the orange, and where it is successfully grown it is deservedly popular.</p> - -<div class="footnote"> - -<p><a name="Footnote_14" id="Footnote_14"></a><a href="#FNanchor_14"><span class="label">[14]</span></a> <i>Cinnamomum camphora</i> (L.) Nees and Eberm.</p></div> - - -<h3><a id="CHINABERRY"></a>CHINABERRY.</h3> - -<p>The chinaberry,<a name="FNanchor_15" id="FNanchor_15"></a><a href="#Footnote_15" class="fnanchor">[15]</a> sometimes known as the China tree, is a small, -round-headed, short-lived tree that will grow in regions 2, 3, 5, 8, -11, 12, and 13 and near the southern edge of region 6. It is too short -lived to be considered for planting where other trees will grow.</p> - -<div class="footnote"> - -<p><a name="Footnote_15" id="Footnote_15"></a><a href="#FNanchor_15"><span class="label">[15]</span></a> <i>Melia azedarach</i> L .</p></div> - -<p>The umbrella tree,<a name="FNanchor_16" id="FNanchor_16"></a><a href="#Footnote_16" class="fnanchor">[16]</a> or Texas umbrella, is a small, compact form of -the chinaberry with an umbrella-shaped top. It is useful for formal -effects, as in the parking on a wide street where taller trees are used -on the side. It will grow in regions 2, 3, 5, 8, 11, 12, and 13 and in -the southern parts of region 6.</p> - -<div class="footnote"> - -<p><a name="Footnote_16" id="Footnote_16"></a><a href="#FNanchor_16"><span class="label">[16]</span></a> <i>Melia azedarach umbraculiformis</i> Berckmans and Bailey.</p></div> -<p><span class="pagenum"><a name="Page_22" id="Page_22">« 22 »</a></span></p> - -<h3><a id="ELM"></a>ELM.</h3> - -<p>The elms are large, handsome shade trees suitable for use over a -wide range of territory.</p> - -<div class="fig_center" style="width: 448px;"><a id="Fig_18"></a> -<img src="images/fig18.png" width="448" height="600" alt="" /> -<div class="phnum">P12460HP</div> - -<div class="fig_caption"><span class="smcap">Fig. 18.</span>—An American elm with crotches liable to be split by heavy winds. Note the supporting -chains.</div> -</div> - -<p>The American elm<a name="FNanchor_17" id="FNanchor_17"></a><a href="#Footnote_17" class="fnanchor">[17]</a> sometimes called the white elm and water elm, -is one of the handsomest American shade trees. (<a href="#Fig_3">fig. 3.</a>) It has<span class="pagenum"><a name="Page_23" id="Page_23">« 23 »</a></span> -been the standard street tree of New England, giving to the roadsides -and village streets the characteristic appearance which is so attractive -to summer visitors.</p> - -<div class="footnote"> - -<p><a name="Footnote_17" id="Footnote_17"></a><a href="#FNanchor_17"><span class="label">[17]</span></a> <i>Ulmus americana</i></p></div> - -<p>The American elm is tall and spreading, and where planted as near -together as is customary on streets and country roads the effect of -the mature trees is that of an arch formed by the growing together -of their spreading tops. It is of rapid growth and long lived.</p> - -<p>This elm drops its leaves very early in the fall, but it comes into -leaf early in the spring. Because of its manner of branching it is -especially liable to be split by heavy winds. This trouble may be -lessened by selecting and planting specimens with a close, compact -habit of growth or possibly also by great care in training young trees. -Two limbs separating from one another by a very small angle, that -is, when they start to grow in nearly the same direction, make a -crotch that is liable to split. (<a href="#Fig_18">fig. 18</a>) Where two limbs separate -at nearly a right angle or where three or more limbs of about equal -size grow from a common point or very nearly so, the crotch is likely -to be much stronger. Careful pruning and training to provide a -proper system of branches may be especially helpful with this elm.</p> - -<p>Because of the attacks of the elm leaf-beetle<a name="FNanchor_18" id="FNanchor_18"></a><a href="#Footnote_18" class="fnanchor">[18]</a> and the European -elm bark louse,<a name="FNanchor_19" id="FNanchor_19"></a><a href="#Footnote_19" class="fnanchor">[19]</a> many handsome trees have been severely damaged -or killed before communities were properly equipped for fighting -them, for with careful spraying these insects may be kept in check. -However, on account of the existence of these pests and because -they are gradually spreading to new territory, tree planters should -consider carefully whether it is advisable to plant the elm in their -localities. Where there is no danger from these insects, this elm is -one of the best of street trees. Consultation with the nearest State -agricultural experiment station or with the Entomologist of the -United States Department of Agriculture would be advisable in order -to determine this point.</p> - -<div class="footnote"> - -<p><a name="Footnote_18" id="Footnote_18"></a><a href="#FNanchor_18"><span class="label">[18]</span></a> <i>Galcrucella luteola</i> Mull.</p></div> - -<div class="footnote"> - -<p><a name="Footnote_19" id="Footnote_19"></a><a href="#FNanchor_19"><span class="label">[19]</span></a> <i>Gossyparia spuria</i> Mod. (Data regarding both -insects furnished by the Bureau of Entomology.)</p></div> - -<p>The best specimens are to be found in the northern part of region -10, although the elm is being grown all over the United States and -is proving a valuable street tree even in towns and villages of regions -where the rainfall is as low as 15 inches. It is not recommended -for planting in regions 3 and 5.</p> - -<p>The English elm<a name="FNanchor_20" id="FNanchor_20"></a><a href="#Footnote_20" class="fnanchor">[20]</a> is a tall, oval-headed, compact, handsome tree -with leaves smaller than the American elm and which stay on much -later in the fall. In regions 1 and 2 it is at its best, in the former -equaling the American elm and in the latter excelling it. It also -thrives in regions 3 and 10 and in the eastern part of region 11.</p> - -<div class="footnote"> - -<p><a name="Footnote_20" id="Footnote_20"></a><a href="#FNanchor_20"><span class="label">[20]</span></a> <i>Ulmus campestris</i> L.</p></div> - -<p>The Huntingdon elm<a name="FNanchor_21" id="FNanchor_21"></a><a href="#Footnote_21" class="fnanchor">[21]</a> is a comparatively round-headed European -variety.</p> - -<div class="footnote"> - -<p><a name="Footnote_21" id="Footnote_21"></a><a href="#FNanchor_21"><span class="label">[21]</span></a> <i>Ulmus hollandica vegeta</i> (Lindl.) Rend.</p></div> - -<p><span class="pagenum"><a name="Page_24" id="Page_24">« 24 »</a></span></p> - -<p>It is a large, handsome tree with good foliage and is more compact -in growth than the American elm. It succeeds well in regions 1, 2, -3, and 4.</p> - -<p>The wahoo, or winged elm,<a name="FNanchor_22" id="FNanchor_22"></a><a href="#Footnote_22" class="fnanchor">[22]</a> is native to the South Atlantic and -Gulf States near the ocean. It has larger leaves than the American -elm and is not as spreading in its growth, but it succeeds well on city -streets in regions 11, 12, and 13.</p> - -<div class="footnote"> - -<p><a name="Footnote_22" id="Footnote_22"></a><a href="#FNanchor_22"><span class="label">[22]</span></a> <i>Ulmus alata</i> Michx.</p></div> - - -<h3><a id="EUCALYPTUS"></a>EUCALYPTUS.</h3> - -<p>There are a large number of species of Eucalyptus, many of which -can be used for street planting in regions 2, 3, and 5. Some cities -prohibit their planting because their roots are liable to penetrate -defective sewers, and in other cities they must be kept at least 70 feet -from a sewer, though even this distance may not prove permanently -effective.</p> - -<p>The roots of any tree are liable to find their way into a defective -sewer, but the trees mentioned are especially noticeable because of -their vigorous root growth. It may be questioned whether a tree -should be condemned for this growth, as it may be better to have a -defective sewer thus revealed than to continue a menace to public -health.</p> - -<p>Eucalypti are also being planted in southern Florida, but on account -of the moist climate there it is not to be expected that they will -succeed as well as in the other regions mentioned. They are tall, -handsome, quick-growing trees, usually bearing two kinds of leaves -at some time in their development.</p> - -<p>The blue gum<a name="FNanchor_23" id="FNanchor_23"></a><a href="#Footnote_23" class="fnanchor">[23]</a> is one of the best eucalypti and the one most commonly -used in California. It is tall, globular headed, handsome, and -will survive several degrees of frost, but it will not withstand the heat -of the deserts in region 5. Its roots are especially liable to invade -sewers.</p> - -<div class="footnote"> - -<p><a name="Footnote_23" id="Footnote_23"></a><a href="#FNanchor_23"><span class="label">[23]</span></a> <i>Eucalyptus globulus</i> Labill.</p></div> - -<p>The desert gum<a name="FNanchor_24" id="FNanchor_24"></a><a href="#Footnote_24" class="fnanchor">[24]</a> is one of the trees most resistant to heat and cold, -and it makes a handsome avenue tree. It has pendent branches that -have a tendency to severe splitting with age, but with early attention -this may be overcome largely. It may prove especially valuable -for region 5.</p> - -<div class="footnote"> - -<p><a name="Footnote_24" id="Footnote_24"></a><a href="#FNanchor_24"><span class="label">[24]</span></a> <i>Eucalyptus rudis</i> Endl.</p></div> - -<p>The manna gum<a name="FNanchor_25" id="FNanchor_25"></a><a href="#Footnote_25" class="fnanchor">[25]</a> is another Eucalyptus which withstands several -degrees of frost and makes an excellent roadside tree. Some forms -shed their bark in long bands that leave the trunks almost white. -Many people consider it a dirty tree on this account.</p> - -<div class="footnote"> - -<p><a name="Footnote_25" id="Footnote_25"></a><a href="#FNanchor_25"><span class="label">[25]</span></a> <i>Eucalyptus viminalis</i> Labill.</p></div> - -<p>The red gum<a name="FNanchor_26" id="FNanchor_26"></a><a href="#Footnote_26" class="fnanchor">[26]</a> grows with a broad head, is one of the most resistant -of the eucalypti to frost, drought, and heat, and succeeds wherever -any of these trees can be grown in regions 2, 3, or 5, but is most -useful in region 5.</p> - -<div class="footnote"> - -<p><a name="Footnote_26" id="Footnote_26"></a><a href="#FNanchor_26"><span class="label">[26]</span></a> <i>Eucalyptus longirostris</i> F. Muell.</p></div> - -<p><span class="pagenum"><a name="Page_25" id="Page_25">« 25 »</a></span></p> - -<p>The sugar gum<a name="FNanchor_27" id="FNanchor_27"></a><a href="#Footnote_27" class="fnanchor">[27]</a> is a drought-resistant variety, but it does not -withstand cold. It is a common roadside tree in southern California, -but becomes straggling with age.</p> - -<div class="footnote"> - -<p><a name="Footnote_27" id="Footnote_27"></a><a href="#FNanchor_27"><span class="label">[27]</span></a> <i>Eucalyptus corynocalyx</i> F. Muell.</p></div> - - -<h3><a id="GINKGO"></a>GINKGO.</h3> - -<p>The ginkgo,<a name="FNanchor_28" id="FNanchor_28"></a><a href="#Footnote_28" class="fnanchor">[28]</a> or maidenhair tree (<a href="#Fig_4">fig. 4, <i>B</i></a>), is a native of Japan that -thrives in a cool climate or a hot, moist one and succeeds in regions -1, 9, 10, 11, 12, and 13. It is extremely erratic in its behavior, sometimes -growing well, sometimes practically not growing at all, but -where it succeeds it is very disease resistant, and it withstands -severe windstorms remarkably well. The leaf is peculiar in appearance, -resembling in outline a much enlarged leaflet of maidenhair -fern with a corrugated surface. The tree is conical when young, but -as it reaches maturity its top usually fills out, making a broad, almost -flat-topped, handsome tree. Only the staminate form should be -used, because the pistillate form bears fruits the flesh of which is -slippery and dangerous when it drops to the pavement, and to some -people it is somewhat poisonous to the touch. Ginkgo trees, therefore, -would need to be secured by budding or grafting from the -mature staminate form.</p> - -<div class="footnote"> - -<p><a name="Footnote_28" id="Footnote_28"></a><a href="#FNanchor_28"><span class="label">[28]</span></a> <i>Ginkgo biloba</i> L.</p></div> - - -<h3><a id="HACKBERRIES"></a>HACKBERRIES.</h3> - -<p>The hackberry,<a name="FNanchor_29" id="FNanchor_29"></a><a href="#Footnote_29" class="fnanchor">[29]</a> or sugarberry, is especially valuable in regions -6, 7, 8, and 9, as it grows satisfactorily where there is comparatively -slight rainfall. It is also much used in region 11, but should be superseded -there by other varieties that are better. It is of moderate size -with an oblong head and of rather open growth. It is comparatively -short lived. Its leaves are much like those of the elm.</p> - -<div class="footnote"> - -<p><a name="Footnote_29" id="Footnote_29"></a><a href="#FNanchor_29"><span class="label">[29]</span></a> <i>Celtis occidentalis</i> L.</p></div> - -<p>The name sugarberry comes from the sweet black berries that are -borne in the early fall. The tree is sometimes affected by a fungous -trouble known as witches'-broom. This trouble causes large numbers -of small sprouts to start from the affected portion, which gives the -infected tree an unsightly appearance. The hackberry should not -be planted where this trouble is prevalent.</p> - -<p>The Mississippi hackberry<a name="FNanchor_30" id="FNanchor_30"></a><a href="#Footnote_30" class="fnanchor">[30]</a> is a large, open, oblong-headed tree -with smoother leaves than the common hackberry. It is useful in -the southern part of region 6, in region 8, and to some extent in regions -11 and 12. It thrives well under the same adverse moisture conditions -as the common hackberry. The trunk and the large branches -have little wartlike projections of the bark scattered irregularly over -them. The small twigs are sometimes more or less spotted or winged -in the same way. The tree is rather larger than the common hackberry -and apparently is less subject to witches'-broom.</p> - -<div class="footnote"> - -<p><a name="Footnote_30" id="Footnote_30"></a><a href="#FNanchor_30"><span class="label">[30]</span></a> <i>Celtis mississippiensis</i> Bosc.</p></div> - -<p><span class="pagenum"><a name="Page_26" id="Page_26">« 26 »</a></span></p> - - -<h3><a id="HONEY_LOCUST"></a>HONEY LOCUST.</h3> - -<p>The honey locust<a name="FNanchor_31" id="FNanchor_31"></a><a href="#Footnote_31" class="fnanchor">[31]</a> is a large, open, round-headed, fine-foliaged tree, -admitting much light through its top. (<a href="#Fig_19">fig. 19</a>) The common -form has stiff spines 2 to 6 inches long, or even longer. There is also -a form without spines, which is the one that should be used for street -planting. It is a useful tree in regions 1, 2, 3, 9, 10, and 11, but is -especially valuable for planting in regions 6, 7, and 8, and may -prove useful in region 5.</p> - -<div class="footnote"> - -<p><a name="Footnote_31" id="Footnote_31"></a><a href="#FNanchor_31"><span class="label">[31]</span></a> <i>Gleditsia triacanthos</i> L.</p></div> - -<div class="fig_center" style="width: 478px;"><a id="Fig_19"></a> -<img src="images/fig19.png" width="478" height="340" alt="" /> -<div class="fig_caption"><span class="smcap">Fig. 19.</span>—A street shaded with honey locusts, as seen in late summer. Washington, D. C.</div> -</div> - - -<h3><a id="HORSE-CHESTNUT"></a>HORSE-CHESTNUT.</h3> - -<p>The horse-chestnut<a name="FNanchor_32" id="FNanchor_32"></a><a href="#Footnote_32" class="fnanchor">[32]</a> has handsome blossoms that are very showy, -and when in bloom an avenue of these trees commands attention. -It is a close relative of the buckeye, or Ohio buckeye, which is also -a handsome tree, though less desirable. It is objectionable because -it is likely to be broken by boys clubbing it for its nuts, which are -inedible, or where its leaves are affected with a midsummer blight -which makes it unsightly during the remainder of the season. It is -a medium-sized round-headed tree that does much better under -suburban than under city conditions. It thrives in regions 1, 2, -3, and 10.</p> - -<div class="footnote"> - -<p><a name="Footnote_32" id="Footnote_32"></a><a href="#FNanchor_32"><span class="label">[32]</span></a> <i>Aesculus hippocastanum</i> L.</p></div> - -<p><span class="pagenum"><a name="Page_27" id="Page_27">« 27 »</a></span></p> - - -<h3><a id="LINDEN"></a>LINDEN.</h3> - -<p>The basswood,<a name="FNanchor_33" id="FNanchor_33"></a><a href="#Footnote_33" class="fnanchor">[33]</a> or linden, is a large round-headed tree that is -excellent for roadsides in suburban locations and does well on city -streets if the conditions are not too severe. On account of the dark -upper surface and the lighter under surface of the leaves and the -sweet-scented blossoms in early summer it is much admired. It is -not as reliable as some of the other shade trees, as when young it is -sometimes attacked at the base of the trunk by a fungous growth -that kills the tree. When once established it forms handsome avenues. -It is suited to regions 1, 2, 3, 4, 7, 9, 10, and 11.</p> - -<div class="footnote"> - -<p><a name="Footnote_33" id="Footnote_33"></a><a href="#FNanchor_33"><span class="label">[33]</span></a> <i>Tilia americana</i> L.</p></div> - -<p>The linden,<a name="FNanchor_34" id="FNanchor_34"></a><a href="#Footnote_34" class="fnanchor">[34]</a> or European linden, has much smaller leaves than the -American linden, or basswood, with more contrast between their -upper and lower surfaces. It is not much different in size, but is -a little more compact in growth and holds its leaves longer in the -fall. It is a useful tree for street planting in regions 1, 2, 3, 4, 9, -10, and 11.</p> - -<div class="footnote"> - -<p><a name="Footnote_34" id="Footnote_34"></a><a href="#FNanchor_34"><span class="label">[34]</span></a> <i>Tilia platyphyllos</i> Scop.</p></div> - - -<h3><a id="LOCUST"></a>LOCUST.</h3> - -<p>The locust,<a name="FNanchor_35" id="FNanchor_35"></a><a href="#Footnote_35" class="fnanchor">[35]</a> or black locust, is one of the desirable street trees in -regions 6, 7, 8, and probably in region 5, as it thrives with comparatively -little moisture. It makes a moderate-sized oval head -that bears sweet-scented white flowers in late spring or early summer. -Its greatest drawback is its liability to serious injury and disfigurement -by the locust borer,<a name="FNanchor_36" id="FNanchor_36"></a><a href="#Footnote_36" class="fnanchor">[36]</a> but with proper care this injury can be -prevented.<a name="FNanchor_37" id="FNanchor_37"></a><a href="#Footnote_37" class="fnanchor">[37]</a> In some parts of the East it is also subject to a leaf -miner<a name="FNanchor_38" id="FNanchor_38"></a><a href="#Footnote_38" class="fnanchor">[38]</a> that gives its foliage a burned appearance. In region 3 it -holds its seed pods for several years and thus becomes very unsightly.</p> - -<div class="footnote"> - -<p><a name="Footnote_35" id="Footnote_35"></a><a href="#FNanchor_35"><span class="label">[35]</span></a> <i>Robinia pseudacacia</i> L.</p></div> - -<div class="footnote"> - -<p><a name="Footnote_36" id="Footnote_36"></a><a href="#FNanchor_36"><span class="label">[36]</span></a> <i>Cylene robiniae</i> Forst. (Data furnished by the Bureau of Entomology).</p></div> - -<div class="footnote"> - -<p><a name="Footnote_37" id="Footnote_37"></a><a href="#FNanchor_37"><span class="label">[37]</span></a> See U. S. Dept. of Agriculture Bulletin 787, entitled "Protection from the Locust Borer."</p></div> - -<div class="footnote"> - -<p><a name="Footnote_38" id="Footnote_38"></a><a href="#FNanchor_38"><span class="label">[38]</span></a> <i>Chalepis dorsalis</i> Thunb.</p></div> - - -<h3><a id="MAGNOLIA"></a>MAGNOLIA.</h3> - -<p>The evergreen magnolia<a name="FNanchor_39" id="FNanchor_39"></a><a href="#Footnote_39" class="fnanchor">[39]</a> is one of the few good evergreen trees -for street planting, but it is adapted only to regions 1, 2, 3, 11, 12, -and 13. There are but few conditions that warrant the planting -of a tree having foliage as thick as this, because of the dense shade, -which is especially undesirable in winter. It grows to be a large -oval-headed tree and bears beautiful large white blossoms in late -spring or early summer.</p> - -<div class="footnote"> - -<p><a name="Footnote_39" id="Footnote_39"></a><a href="#FNanchor_39"><span class="label">[39]</span></a> <i>Magnolia grandifolia</i> L.</p></div> - - -<h3><a id="MAPLE"></a>MAPLE.</h3> - -<p>Among the maples are some undesirable trees much used for -street planting and some that are valuable only in restricted areas -or under special conditions. The maples are not as satisfactory for -<span class="pagenum"><a name="Page_28" id="Page_28">« 28 »</a></span> -street planting as usually has been supposed, few of the species -being suitable for this purpose and these only in a limited way. -The ash-leaved maple, or box elder,<a name="FNanchor_40" id="FNanchor_40"></a><a href="#Footnote_40" class="fnanchor">[40]</a> is native to all of the country -east of the Rocky Mountains except the regions near the South -Atlantic and Gulf coasts. It is a small, quick-growing tree that will -thrive almost anywhere, but it reaches maturity early. Because of its -early decay and of its being subject to destruction by wind, it should -not be used for street planting where other trees succeed. It would be -a good tree for interplanting -were it safe -to risk taking out -some of the trees at -the right time. The -objection to using -these trees is that -they would be so -likely to look larger -and better than the -permanent trees at -the time they should -be removed that public -opinion would -probably resent their -removal. There may -be conditions requiring -the use of this tree -in regions 6, 7, and 8, -but it should be grown -only when the other -trees suggested for -these regions will not -succeed.</p> - -<div class="footnote"> - -<p><a name="Footnote_40" id="Footnote_40"></a><a href="#FNanchor_40"><span class="label">[40]</span></a> <i>Acer negundo</i> L.</p></div> - -<p>The English maple<a name="FNanchor_41" id="FNanchor_41"></a><a href="#Footnote_41" class="fnanchor">[41]</a> -is small, round-headed, -with small dark-green -leaves, useful in regions -1, 2, 3, and 4.</p> - -<div class="footnote"> - -<p><a name="Footnote_41" id="Footnote_41"></a><a href="#FNanchor_41"><span class="label">[41]</span></a> <i>Acer campestre</i> L.</p></div> - -<div class="fig_left" style="width: 321px;"><a id="Fig_20"></a> -<img src="images/fig20.png" width="321" height="447" alt="" /> -<div class="phnum">P20042HP</div> - -<div class="fig_caption"><span class="smcap">Fig. 20.</span>—A Norway maple, as seen in late winter, showing its poor -shape when trimmed to a high head.</div> -</div> - -<p>The Norway maple<a name="FNanchor_42" id="FNanchor_42"></a><a href="#Footnote_42" class="fnanchor">[42]</a> is round-headed and eventually reaches -large size, but, as compared with most of the other maples, it is -slow growing (<a href="#Fig_4">fig. 4, <i>C</i></a>). The persistence of its tendency to form -a low head makes it difficult to give it a high head of desirable shape -(<a href="#Fig_20">fig. 20</a>). It is also very thickly branched, and its foliage, being -heavy and dark-green, permits but little light to pass through. On -this account it is rather undesirable for street planting. By severe -pruning of the interior of the head this defect may be somewhat -<span class="pagenum"><a name="Page_29" id="Page_29">« 29 »</a></span> -overcome. The tree is practically disease and insect free, with the -exception of a liability to infestation by a leaf aphis<a name="FNanchor_43" id="FNanchor_43"></a><a href="#Footnote_43" class="fnanchor">[43]</a> which produces -yellow spots on the leaves and causes them to drop prematurely; -also, the honeydew which they produce is so abundant at -times as to cover the leaves and wet the sidewalk beneath the -tree, the leaves under certain weather conditions becoming blackened -with dust accumulating and a fungus growing in the secretion, -thereby giving the tree an unsightly appearance. This aphis, however, -is not always present and does not seriously injure the tree. -The Norway maple comes into leaf later than most of the other -maples, but holds its leaves later in the fall. They usually assume -a bright yellow hue before they drop. The leaves are preceded -by an abundance of yellow-green blossoms. On account of its dense -shade and masses of fine fibrous roots it is difficult to grow grass -under this tree. Its good shape and attractive dark-green foliage -make it popular for street planting in spite of its dense, low head. -It will succeed in regions 1, 2, 3, 4, 9, 10, 11, and 12.</p> - -<div class="footnote"> - -<p><a name="Footnote_42" id="Footnote_42"></a><a href="#FNanchor_42"><span class="label">[42]</span></a> <i>Acer platanoides</i> L.</p></div> - -<div class="footnote"> - -<p><a name="Footnote_43" id="Footnote_43"></a><a href="#FNanchor_43"><span class="label">[43]</span></a> <i>Periphyllus lyropictus</i> Kess. (Data furnished by the Bureau of Entomology.)</p></div> - -<p>The Oregon maple<a name="FNanchor_44" id="FNanchor_44"></a><a href="#Footnote_44" class="fnanchor">[44]</a> is the large-leaved maple of the northern -Pacific slope. It forms a large round head, and with its unusually -large dark-green leaves makes a very attractive street tree that -succeeds well in regions 1, 2, 3, and 4. It is valuable and worthy -of more extended cultivation on the Pacific coast.</p> - -<div class="footnote"> - -<p><a name="Footnote_44" id="Footnote_44"></a><a href="#FNanchor_44"><span class="label">[44]</span></a> <i>Acer macrophyllum</i> Pursh.</p></div> - -<p>The red maple,<a name="FNanchor_45" id="FNanchor_45"></a><a href="#Footnote_45" class="fnanchor">[45]</a> scarlet maple, or swamp maple is one of the -most widely distributed of American trees. It is found from Canada -to the Gulf of Mexico and west to the Rocky Mountains. Its leaves -are the smallest of any of the eastern native maples, but it grows -large and the trees are usually of rather upright outline. It is -better adapted to suburban conditions than to city streets and is -one of the few trees that succeed well near the ocean. It has bright-red -blossoms before the leaves appear. The young leaves and fruits -are also red. The mature leaves begin to color early, some branches -coloring as early as the middle of July, assuming brilliant reds and -yellows and staying on later than those of the sugar maple. It is -a handsome tree that is not as much used as it deserves to be in -regions 1, 9, 10, 11, 12, and 13.</p> - -<div class="footnote"> - -<p><a name="Footnote_45" id="Footnote_45"></a><a href="#FNanchor_45"><span class="label">[45]</span></a> <i>Acer rubrum</i> L.</p></div> - -<div class="fig_left" style="width: 328px;"><a id="Fig_21"></a> -<img src="images/fig21.png" width="328" height="427" alt="" /> -<div class="phnum">P12542HP</div> - -<div class="fig_caption"><span class="smcap">Fig. 21.</span>—Silver maples severely headed back, an improper way to -treat trees, especially silver maples, except under very unusual -conditions. Washington, D. C.; midsummer.</div> -</div> - -<p>The silver maple,<a name="FNanchor_46" id="FNanchor_46"></a><a href="#Footnote_46" class="fnanchor">[46]</a> also called the soft maple, white maple, and -swamp maple, is probably more used for street planting through -the whole United States than any other tree, and with one exception -it is the least desirable. It is usually planted because it is a -quick-growing tree, but it is not more rapid in growth than several -other much better trees. There are three serious objections to its -use as a street tree. The first is its brittle wood, which at an early -<span class="pagenum"><a name="Page_30" id="Page_30">« 30 »</a></span> -age is easily broken by ordinary windstorms and causes it when -a comparatively young tree to become unsightly. The second is -its shallow rooting, which has a tendency to destroy pavements -and also makes it difficult to grow grass near the trees. The roots also -will grow into sewers. The third is the tendency to decay; the -tips of the limbs frequently die, leaving the whole top of the tree -bare of leaves, and the wood decays quickly, especially if the bark -is broken. For this reason it does not stand pruning as well as most -other street trees, and it probably has been pruned more ruthlessly -than any other tree, -unless it is the Carolina -poplar. It should -never be severely deheaded -or, as it is -popularly called, "dehorned" -(<a href="#Fig_21">fig. 21</a>), as -the stubs will practically -never heal over, -and from these cuts -decay will start, which -in a very few years will -rot the center of the -limbs and trunk and -thus destroy the tree. -Although it forms a -large round head with -an open top and its -foliage is pale green -above and almost -white beneath, making -a very delightful shade, on account -of its weaknesses it -should never be used -for street planting -where other trees can -be made to grow.</p> - -<div class="footnote"> - -<p><a name="Footnote_46" id="Footnote_46"></a><a href="#FNanchor_46"><span class="label">[46]</span></a> <i>Acer saccharinum</i> L.</p></div> - -<p>The sugar maple,<a name="FNanchor_47" id="FNanchor_47"></a><a href="#Footnote_47" class="fnanchor">[47]</a> or hard maple, is especially adapted to gravelly -soils in regions 1, 10, and 11, the northern parts of regions 2 and 3, -and the eastern and southern parts of region 9. It is oval-headed, -large, and handsome, having red blossoms which individually are -inconspicuous but which in mass are showy early in the spring -before the leaves appear. The leaves come early, but in late summer -they begin to turn brilliant yellow and red and drop before most -other leaves. The sugar maple does not thrive under city conditions, -but is admirably adapted to suburban conditions.</p> - -<div class="footnote"> - -<p><a name="Footnote_47" id="Footnote_47"></a><a href="#FNanchor_47"><span class="label">[47]</span></a> <i>Acer saccharum</i> Marsh.</p></div> - -<p><span class="pagenum"><a name="Page_31" id="Page_31">« 31 »</a></span></p> - -<p>Although the sycamore maple<a name="FNanchor_48" id="FNanchor_48"></a><a href="#Footnote_48" class="fnanchor">[48]</a> is similar in appearance to the -Norway maple, it is not a satisfactory street tree in the eastern -United States. It succeeds, however, in regions 1, 2, 3, and 4.</p> - -<div class="footnote"> - -<p><a name="Footnote_48" id="Footnote_48"></a><a href="#FNanchor_48"><span class="label">[48]</span></a> <i>Acer pseudoplatanus</i> L.</p></div> - -<div class="fig_right" style="width: 318px;"><a id="Fig_22"></a> -<img src="images/fig22.png" width="318" height="390" alt="" /> -<div class="phnum">P15662HP</div> - -<div class="fig_caption"><span class="smcap">Fig. 22.</span>—A sugar maple (on the left) and a white oak (on the right), -each 32 years old and nearly the same size.</div> -</div> - - -<h3><a id="OAK"></a>OAK.</h3> - -<p>Of the trees used for street planting the oaks are best. They -probably have not been more widely planted because of the prevalent -belief that they are slow growers and because in the North they -are rather difficult to transplant. Although some of the handsomest -species, like the white oak and live oak, are slow growers, -those suitable for street -planting are comparatively -rapid-growing. -The white oak and sugar -maple shown in figure -22 are each 32 years -old and although differing -in shape are practically -the same size, -yet the sugar maple -is considered a sufficiently -rapid-growing -tree to be planted frequently -as a street -tree, while the white -oak is seldom so used. -The oaks are hardy, -most of them are long -lived, and for the most -part they are free from -disease and insect attacks. -Some of the -southern species are -subject to attacks of -mistletoe.</p> - -<p>The California live oak<a name="FNanchor_49" id="FNanchor_49"></a><a href="#Footnote_49" class="fnanchor">[49]</a> is an evergreen suitable for use in region 2 -and succeeds adjacent to the ocean. It is also useful in region 3 -and in the western part of region 5. It is easily transplanted if -handled young, and especially so when planted from pots.</p> - -<div class="footnote"> - -<p><a name="Footnote_49" id="Footnote_49"></a><a href="#FNanchor_49"><span class="label">[49]</span></a> <i>Quercus agrifolia</i> Nee.</p></div> - -<p>The chestnut oak<a name="FNanchor_50" id="FNanchor_50"></a><a href="#Footnote_50" class="fnanchor">[50]</a> is a native of gravelly soils on eastern mountains -and is suitable for gravelly soils in suburban locations in -regions 9, 10, and 11. It is a large, handsome tree.</p> - -<div class="footnote"> - -<p><a name="Footnote_50" id="Footnote_50"></a><a href="#FNanchor_50"><span class="label">[50]</span></a> <i>Quercus montana</i> Willd. (formerly <i>Q. prinus</i>).</p></div> - -<p>The Darlington oak<a name="FNanchor_51" id="FNanchor_51"></a><a href="#Footnote_51" class="fnanchor">[51]</a> is a form of laurel oak especially desirable -for street planting. It is large, round-headed; the leaves are a trifle<span class="pagenum"><a name="Page_32" id="Page_32">« 32 »</a></span> -smaller and not quite so nearly evergreen as the laurel oak. It -is found wild about Darlington, S. C., where a good form of the laurel -oak appears to have been introduced as a shade tree in the early -part of the nineteenth century. (<a href="#Fig_23">fig. 23</a>) Its range of usefulness -lies in regions 11 and 12.</p> - -<div class="footnote"> - -<p><a name="Footnote_51" id="Footnote_51"></a><a href="#FNanchor_51"><span class="label">[51]</span></a> <i>Quercus laurifolia</i> Michx.</p></div> - -<p>The laurel oak<a name="FNanchor_52" id="FNanchor_52"></a><a href="#Footnote_52" class="fnanchor">[52]</a> is a large, oval-headed tree that is not as rugged -and irregular as the live oak, but is suitable for street planting in -regions 11, 12, and 13. It has large, thick, glossy leaves, and in -the warmer regions it is almost evergreen. It is readily transplanted, -but as it is not so common in the woods as the willow oak -and the water oak, it has not been so much used as a street tree.</p> - -<div class="footnote"> - -<p><a name="Footnote_52" id="Footnote_52"></a><a href="#FNanchor_52"><span class="label">[52]</span></a> <i>Quercus laurifolia</i> Michx.</p></div> - -<div class="fig_center" style="width: 480px;"><a id="Fig_23"></a> -<img src="images/fig23.png" width="480" height="411" alt="" /> -<div class="phnum">P15461HP</div> - -<div class="fig_caption"><span class="smcap">Fig. 23.</span>—A Darlington oak as seen in late summer, Darlington. S. C.</div> -</div> - -<p>The live oak<a name="FNanchor_53" id="FNanchor_53"></a><a href="#Footnote_53" class="fnanchor">[53]</a> (<a href="#Fig_16">fig. 16</a>) is probably the noblest and most majestic -of the oaks of regions 12 and 13. It is evergreen and of slow growth, -but wherever it is found, whether on streets or in public parks, it is -the pride of the people. Although an evergreen it is sufficiently -open-headed to make a good street tree. When it becomes old it is -spreading and as a rule does not form as high a head as the willow -oak and the laurel oak. Compared with other southern oaks it is -difficult to transplant. It is of sufficient merit to be used on broad -streets, and especially on boulevards, where the good of the future -as well as the present is considered.</p> - -<div class="footnote"> - -<p><a name="Footnote_53" id="Footnote_53"></a><a href="#FNanchor_53"><span class="label">[53]</span></a> <i>Quercus virginiana</i> Mill.</p></div> - -<p><span class="pagenum"><a name="Page_33" id="Page_33">« 33 »</a></span></p> - -<div class="fig_center" style="width: 480px;"><a id="Fig_24"></a> -<img src="images/fig24.png" width="480" height="303" alt="" /> -<div class="phnum">P14413HP</div> - -<div class="fig_caption"><span class="smcap">Fig. 24.</span>—A street shaded with red oaks, Washington, D. C.; midsummer.</div> -</div> - -<p>The burr oak,<a name="FNanchor_54" id="FNanchor_54"></a><a href="#Footnote_54" class="fnanchor">[54]</a> or mossy-cup oak, is native in the northeastern -United States and west of the Mississippi River on the hills lying -between the river bottoms and the prairies west to the western parts -of the Dakotas and Nebraska and central Kansas and Texas. It is a -large; handsome tree that should prove satisfactory under suburban -conditions in regions 7, 8, 9, 10, and 11 and on fertile well-watered soils.</p> - -<div class="footnote"> - -<p><a name="Footnote_54" id="Footnote_54"></a><a href="#FNanchor_54"><span class="label">[54]</span></a> <i>Quercus macrocarpa</i> Michx.</p></div> - -<p>The pin oak,<a name="FNanchor_55" id="FNanchor_55"></a><a href="#Footnote_55" class="fnanchor">[55]</a> sometimes called the swamp oak, is a tall tree, conical -when young, oval at maturity, with a drooping habit of the lower -branches. The leaves are quite finely divided and are of a bright -glossy green. The tree comes into leaf late in the spring and holds its -foliage late in the fall. One objection to the pin oak for street -planting is that on many specimens the dead leaves hang on through -the winter. It is adapted to narrower streets than the red oak, as its -habit of growth is not so spreading. On account of the tendency of -the limbs to droop, particularly as they get older, it is desirable -that a good strong leader should be developed, so that the lower -limbs may be removed from time to time as conditions require. -The pin oak thrives on wet and on heavy clay soils, as well as on a -wide range of other soils. <a href="#Fig_4">Figure 4</a> shows pin oaks, Norway maples, -and ginkgos 18 years old on adjacent streets, and illustrates the -rapid growth of this oak. At the time of planting these trees the pin -oaks were thought to have the poorest location. This tree is adapted -to regions 1, 2, 3, 4, 9, 10, and 11.</p> - -<div class="footnote"> - -<p><a name="Footnote_55" id="Footnote_55"></a><a href="#FNanchor_55"><span class="label">[55]</span></a> <i>Quercus palustris</i> L.</p></div> - -<p><span class="pagenum"><a name="Page_34" id="Page_34">« 34 »</a></span></p> - -<p>The red oak<a name="FNanchor_56" id="FNanchor_56"></a><a href="#Footnote_56" class="fnanchor">[56]</a> (<a href="#Fig_24">fig. 24</a>) is probably the best tree for street planting -in regions 1, 9, 10, and 11 and is satisfactory in regions 6, 7, 8, and 12. -It is a large, oval, open-headed tree of rapid growth. Under good -conditions a young red oak will grow 4 feet in a single season. Like -the other oaks it is slow in coming into leaf in the spring, but holds -its foliage late in the fall. The leaves usually turn a brilliant red -before they drop. It is comparatively free from insect and fungous -attacks, and it is one of the few trees really suitable for planting close -to the ocean, as it thrives on sandy lands only a few feet above high -tide or within the reach of ocean spray.</p> - -<div class="footnote"> - -<p><a name="Footnote_56" id="Footnote_56"></a><a href="#FNanchor_56"><span class="label">[56]</span></a> <i>Quercus maxima</i> (March.) Ashe (formerly <i>Q. rubra</i>).</p></div> - -<p>The scarlet oak<a name="FNanchor_57" id="FNanchor_57"></a><a href="#Footnote_57" class="fnanchor">[57]</a> is a large, open, round-headed tree. Its leaves -are more deeply divided than those of the red oak. As its name -indicates, the leaves turn a brilliant scarlet in autumn, being even -more gorgeous than the red oak. This tree is adapted for street -planting and is especially desirable for suburban conditions in regions -1, 9, and 10.</p> - -<div class="footnote"> - -<p><a name="Footnote_57" id="Footnote_57"></a><a href="#FNanchor_57"><span class="label">[57]</span></a> <i>Quercus coccinea</i> Muench.</p></div> - -<p>The swamp Spanish oak<a name="FNanchor_58" id="FNanchor_58"></a><a href="#Footnote_58" class="fnanchor">[58]</a> is adapted to regions 11, 12, and 13. -It belongs to the red oak group, but is larger than the other oaks -suggested for street planting. It is well adapted to suburban locations, -but apparently it has not been tested under severe city -conditions.</p> - -<div class="footnote"> - -<p><a name="Footnote_58" id="Footnote_58"></a><a href="#FNanchor_58"><span class="label">[58]</span></a> <i>Quercus rubra</i> L. (formerly <i>Q. falcata</i>, and certain forms separated by some botanists as <i>Q. pagodaefolia</i> -Ashe).</p></div> - -<p>The valley oak<a name="FNanchor_59" id="FNanchor_59"></a><a href="#Footnote_59" class="fnanchor">[59]</a> is a beautiful tree for regions 2 and 3 and the more -favorable parts of region 5. When transplanted young, especially -if taken from a pot, it is easily established where there is opportunity -to water it for a few years.</p> - -<div class="footnote"> - -<p><a name="Footnote_59" id="Footnote_59"></a><a href="#FNanchor_59"><span class="label">[59]</span></a> <i>Quercus lobata</i> Nee.</p></div> - -<p>The water oak<a name="FNanchor_60" id="FNanchor_60"></a><a href="#Footnote_60" class="fnanchor">[60]</a> is frequently confused with the willow oak and -the laurel oak, as these three oaks are not distinguished from one -another except by close observers of trees. It is probably more used -than any other tree in the cities of region 12 and the adjoining portions -of region 11. It is the weed of the southern oaks and one of the -weeds of the street trees of the Southern States. It is comparatively -short lived and seems to be more subject to attacks of mistletoe and -more easily affected by windstorms than the willow oak, the Darlington -oak, and the laurel oak. The planting of this tree should be -avoided, because it is less desirable than the other oaks mentioned.</p> - -<div class="footnote"> - -<p><a name="Footnote_60" id="Footnote_60"></a><a href="#FNanchor_60"><span class="label">[60]</span></a> <i>Quercus nigra</i> L.</p></div> - -<p><span class="pagenum"><a name="Page_35" id="Page_35">« 35 »</a></span></p> - -<div class="fig_center" style="width: 512px;"><a id="Fig_25"></a> -<img src="images/fig25.png" width="512" height="738" alt="" /> -<div class="fig_caption"><span class="smcap">Fig. 25.</span>—Leaves of some of the southern oaks; <i>A</i>, Live oak; <i>B</i>, willow oak; <i>C</i>, laurel oak; and <i>D</i>, water oak.</div> -</div> - -<p>The willow oak<a name="FNanchor_61" id="FNanchor_61"></a><a href="#Footnote_61" class="fnanchor">[61]</a> (<a href="#Fig_1">fig. 1</a>), sometimes erroneously called the water -oak, is one of the best of the quick-growing oaks for use in regions -11 and 12. It is frequently used with the water oak for street planting -and in the mind of the average planter is confused with it. It is, -however, a distinct tree, which can be distinguished readily from the -water oak. It is longer lived and is its equal in every other respect. -Trees of this variety which apparently have been planted about -80 years are found in excellent condition, while water oaks planted -at the same time have either entirely disappeared or are showing -<span class="pagenum"><a name="Page_36" id="Page_36">« 36 »</a></span> -marked evidences of decline. <a href="#Fig_25">Figure 25</a> shows the characteristic -appearance of the leaves of these nearly related species of oaks. -That the willow oak is readily transplanted in the South when of -comparatively large size is proved by the success with which trees -12 feet high are dug from the woods and planted on the street -(<a href="#Fig_26">fig. 26</a>). In the extreme South this tree is nearly half evergreen. -Its foliage does not assume the bright colors of the trees of the red oak -class.</p> - -<div class="footnote"> - -<p><a name="Footnote_61" id="Footnote_61"></a><a href="#FNanchor_61"><span class="label">[61]</span></a> <i>Quercus phellos</i> L.</p></div> - -<div class="fig_center" style="width: 488px;"><a id="Fig_26"></a> -<img src="images/fig26.png" width="488" height="353" alt="" /> -<div class="phnum">P15321HP</div> - -<div class="fig_caption"><span class="smcap">Fig. 26.</span>—Recently transplanted willow oaks, showing trees taken from the woods as they appeared -near the end of the second summer. Montgomery, Ala.</div> -</div> - - -<h3><a id="PALM"></a>PALM.<span class="smaller"><a name="FNanchor_62" id="FNanchor_62"></a><a href="#Footnote_62" class="fnanchor">[62]</a></span></h3> - -<div class="footnote"> - -<p><a name="Footnote_62" id="Footnote_62"></a><a href="#FNanchor_62"><span class="label">[62]</span></a> The palms are treated on the basis of notes furnished by Dr. O. F. Cook, of the Bureau of Plant Industry.</p></div> - -<p>Several varieties of palms are used more or less for street planting -in regions 2, 3, 5, 12, and 13. Though sometimes effective as a -formal street decoration (<a href="#Fig_27">fig. 27</a>), they can hardly be considered -shade trees.</p> - - -<h3><a id="PALMETTO"></a>PALMETTO.</h3> - -<p>Palmettos, or sabals, abound in region 12 near the coast; succeed in -regions 3, 5, and 13; live in region 2; but are seldom grown satisfactorily -close to the Pacific coast. They can be used effectively -for formal plantings along some streets, park drives, or in liberal -central parking spaces in boulevards, but they are not useful as a -substitute for shade trees. They should have then leaves and -damaged roots cut off in transplanting and should be set about -3 feet deep in their new location.</p> - -<p><span class="pagenum"><a name="Page_37" id="Page_37">« 37 »</a></span></p> - -<p>The Carolina palmetto<a name="FNanchor_63" id="FNanchor_63"></a><a href="#Footnote_63" class="fnanchor">[63]</a> is a native of and useful in regions 12 and -13, where it sometimes attains a height of 60 or 80 feet. It will -thrive in regions 3 and 5, but is used less there.</p> - -<div class="footnote"> - -<p><a name="Footnote_63" id="Footnote_63"></a><a href="#FNanchor_63"><span class="label">[63]</span></a> <i>Inodes palmetto</i> (Walt.) Cook.</p></div> - -<p>The Texas palmetto<a name="FNanchor_64" id="FNanchor_64"></a><a href="#Footnote_64" class="fnanchor">[64]</a> is especially valuable for southern Texas, -where it is indigenous, and it is likely to succeed generally in regions -3, 5, and 12. It grows to a height of 40 feet and in appearance is -quite distinct from the Carolina palmetto, the leaf segments being -much broader and less drooping.<a name="FNanchor_65" id="FNanchor_65"></a><a href="#Footnote_65" class="fnanchor">[65]</a></p> - -<div class="footnote"> - -<p><a name="Footnote_64" id="Footnote_64"></a><a href="#FNanchor_64"><span class="label">[64]</span></a> <i>Inodes texana</i> Cook.</p></div> - -<div class="footnote"> - -<p><a name="Footnote_65" id="Footnote_65"></a><a href="#FNanchor_65"><span class="label">[65]</span></a> The Texas palmetto. <i>In</i> Jour. Heredity, v. 8, no. 3, p. 123, pl. 1917.</p></div> - -<div class="fig_center" style="width: 472px;"><a id="Fig_27"></a> -<img src="images/fig27.png" width="472" height="307" alt="" /> -<div class="phnum">P18989HP</div> - -<div class="fig_caption"><span class="smcap">Fig. 27.</span>—A formal planting on a city street. Palms with interplantings. -Redlands, Calif., in midsummer.</div> -</div> - -<p>The Victoria palmetto<a name="FNanchor_66" id="FNanchor_66"></a><a href="#Footnote_66" class="fnanchor">[66]</a> is another hardy species, probably a native -of Mexico, but grown for many years at Victoria, Tex. It is similar -to the native Texas species and worthy of general planting in the -same region. A feature of this species is that the persistent leaf -bases remain alive and green for many years instead of turning -yellow or brown, as in the Carolina palmetto.</p> - -<div class="footnote"> - -<p><a name="Footnote_66" id="Footnote_66"></a><a href="#FNanchor_66"><span class="label">[66]</span></a> Cook, O. F. A new ornamental palmetto in southern Texas. <i>In</i> U. S. Dept. Agr., Bur. Plant Indus. -Cir. 113, p. 11-14. 1913.</p></div> - - -<h3><a id="WASHINGTONIA_PALM"></a>WASHINGTONIA PALM.</h3> - -<p>Washingtonia palms are a very conspicuous feature of street and -ornamental planting in southern California. Two species are -represented, <i>Washingtonia filifera</i> Wendland and <i>W. robusta</i> Wendland. -The first is a native of the canyons and barren slopes that -surround the Coachella Valley of southern California, while the other -species probably was brought by way of the Isthmus of Panama -<span class="pagenum"><a name="Page_38" id="Page_38">« 38 »</a></span> -from the region of San Jose del Cabo, the extremity of Lower California, -in the early days of travel. The name <i>robusta</i> alludes to the -fact that this species grows much more rapidly in height than -<i>W. filifera</i>, though the trunk is more slender. Both species are -hardy and thrive well through regions 2, 3, and 5, and also in regions -12 and 13. <i>Washingtonia robusta</i> requires less heat than <i>W. filifera</i>, -but both will endure several degrees of frost. Even in California -<i>Washingtonia robusta</i> is distinctly preferable for localities near the -coast. In the vicinity of San Diego the leaves of <i>Washingtonia filifera</i> -become badly infested with a parasitic fungus that does not attack -<i>Washingtonia robusta</i>.</p> - - -<h3><a id="OTHER_HARDY_FAN_PALMS"></a>OTHER HARDY FAN PALMS.</h3> - -<p>The species most commonly used for street and ornamental planting -in the California coast districts is the Chinese or windmill palm.<a name="FNanchor_67" id="FNanchor_67"></a><a href="#Footnote_67" class="fnanchor">[67]</a> -This palm has a slender trunk clothed with brown fibers, flat fan-shaped -leaves, and rather straight radiating segments. The same -species is hardy at New Orleans and Charleston, and even at Laurens, -S. C., at an altitude of 600 feet, but it does not thrive in the sandy -soil of Florida.</p> - -<div class="footnote"> - -<p><a name="Footnote_67" id="Footnote_67"></a><a href="#FNanchor_67"><span class="label">[67]</span></a> <i>Trachycarpus excelsa</i> (Thunb.) Wendl.</p></div> - -<p>The vegetable hair palm,<a name="FNanchor_68" id="FNanchor_68"></a><a href="#Footnote_68" class="fnanchor">[68]</a> a native of Spain, Sicily, and North -Africa, is similar to the Chinese palm but smaller and more compact -and with large, sharp spines on the petioles of the leaves. When -young it suckers from the base, like the date palm, so that clusters of -it may be formed.</p> - -<div class="footnote"> - -<p><a name="Footnote_68" id="Footnote_68"></a><a href="#FNanchor_68"><span class="label">[68]</span></a> <i>Chamaerops humilis</i> L.</p></div> - -<p>The Guadeloupe Island palm<a name="FNanchor_69" id="FNanchor_69"></a><a href="#Footnote_69" class="fnanchor">[69]</a> is one of the most popular species -in southern California in the region of Santa Barbara, Los Angeles, -and San Diego. This palm is a native of Guadeloupe Island, of! -the coast of lower California, and is not known to occur elsewhere in -the wild state. It is well adapted to the cool coast climate of California, -but not to the interior valleys. It is smaller than the Washingtonia -palms, with a rather short trunk, 15 to 20 feet high, and a -dense crown of fresh green leaves.</p> - -<div class="footnote"> - -<p><a name="Footnote_69" id="Footnote_69"></a><a href="#FNanchor_69"><span class="label">[69]</span></a> <i>Erythea edulis</i> (H. Wendl.) S. Wats.</p></div> - -<p>The California blue palm,<a name="FNanchor_70" id="FNanchor_70"></a><a href="#Footnote_70" class="fnanchor">[70]</a> formerly placed in the same genus with -the Guadeloupe Island species, is very distinct in habits as well as in -general appearance, having bluish or grayish green leaves, strongly -toothed petioles, and long, slender inflorescences. The trunk is -very robust, often 2 to 3 feet in diameter, and is said to attain a -height of 30 to 40 feet in Mexico. Several of these features are shared -with the Washingtonia palms. It also has the ability to grow in the -dry, hot interior valleys (regions 3 and 5). In Texas the blue palm -has proved hardy at San Antonio, and even as far north as Austin.</p> - -<div class="footnote"> - -<p><a name="Footnote_70" id="Footnote_70"></a><a href="#FNanchor_70"><span class="label">[70]</span></a> <i>Glaucothea armata</i> (formerly known as <i>Erythea armata</i>). See Cook, O. F., Glaucothea, a new genus of -palms from Lower California. <i>In</i> Jour. Washington Acad. Sci., v. 5, p. 236-241. 1915.</p></div> - -<p><span class="pagenum"><a name="Page_39" id="Page_39">« 39 »</a></span></p> - -<h3><a id="DATE_PALM"></a>DATE PALM.</h3> - -<p>The Canary Island date palm<a name="FNanchor_71" id="FNanchor_71"></a><a href="#Footnote_71" class="fnanchor">[71]</a> is the most popular palm for park -or street planting, being more hardy than the true date palm, larger -and more vigorous in growth, and producing no suckers from the -base of the trunk. Well-grown specimens in the California coast -districts (region 2) with trunks from 2 to 3 feet thick and immense -crowns of spreading deep-green leaves are among the most imposing -forms of plant life. Though less robust in other regions, the species -is very hardy and adapted for planting anywhere in the palm belt -(regions 3, 5, 12, and 13).</p> - -<div class="footnote"> - -<p><a name="Footnote_71" id="Footnote_71"></a><a href="#FNanchor_71"><span class="label">[71]</span></a> <i>Phoenix canariensis</i> Hort.</p></div> - -<p>The true date palm<a name="FNanchor_72" id="FNanchor_72"></a><a href="#Footnote_72" class="fnanchor">[72]</a> is adapted to the warmer parts of regions 3 -and 5, but it is much inferior to the Canary Island species for ornamental -use because the foliage is less attractive, due to its habit of -sending out suckers from the base of the trunk.</p> - -<div class="footnote"> - -<p><a name="Footnote_72" id="Footnote_72"></a><a href="#FNanchor_72"><span class="label">[72]</span></a> <i>Phoenix dactylifera</i> L.</p></div> - - -<h3><a id="THE_COCONUT"></a>THE COCONUT AND ITS RELATIVES.</h3> - -<p>The true coconut palm is confined to a narrow belt along the coast -of southern Florida, but other species of cocos are planted in the -coast districts of California. The species that is most prominent -in park and street plantings around San Diego, Los Angeles, -and Santa Barbara is usually known as <i>Cocos plumosa</i> or <i>Cocos -romanzoffiana</i>, and is a rather tall, slender palm with a long-jointed -trunk about 1 foot in diameter and long, spreading, feathery, deep-green -leaves. Another series is represented by <i>Cocos yatay</i> and -several similar species, often called <i>Cocos australis</i> in nursery catalogues. -They have short, thick trunks, very glaucous grayish or -bluish foliage, and fleshy edible fruits, highly flavored, somewhat -like pineapples. These gray-leaved species are very hardy. Another -coconut relative is the Chilean molasses palm,<a name="FNanchor_73" id="FNanchor_73"></a><a href="#Footnote_73" class="fnanchor">[73]</a> which has a -massive trunk 3 or 4 feet in diameter, specimens of which are growing -at a few places in California.</p> - -<div class="footnote"> - -<p><a name="Footnote_73" id="Footnote_73"></a><a href="#FNanchor_73"><span class="label">[73]</span></a> <i>Jubaea chilensis</i> Baill.</p></div> - - -<h3><a id="OTHER_PINNATE_PALMS"></a>OTHER PINNATE PALMS.</h3> - -<p>The amethyst palm, a native of Australia, is commonly planted -in California. It usually appears in lists and nursery catalogues -as <i>Seaforthia elegans</i> or <i>Archontophoenix alexandrae</i>, but it is now -recognized as distinct from both of these species and has received -a new name, <i>Loroma amethystina</i>. It is the only pinnate-leaved -palm, except certain species of Phoenix and Cocos, that grows freely -in the open air in the coast districts of California, from Santa Barbara -to San Diego. In habit and general appearance Loroma is -more like the royal palm, though with a smaller trunk and fewer -leaves. The pinkish purple drooping inflorescence is very attractive -and develops into a large cluster of scarlet berries.</p> -<p><span class="pagenum"><a name="Page_40" id="Page_40">« 40 »</a></span></p> - -<p>The royal palms, species of Roystonea, are perhaps the most -striking ornamental members of the whole group. They can be -grown in southern Florida and even exist in the wild state in some -of the hammocks below Miami.</p> - - -<h3><a id="PEPPER_TREE"></a>PEPPER TREE.</h3> - -<p>The California pepper tree<a name="FNanchor_74" id="FNanchor_74"></a><a href="#Footnote_74" class="fnanchor">[74]</a> is much used in regions 2 and 3 and in -the western part of region 5. It is a moderate-sized broad-headed -tree with fine foliage, which gives it a light, airy appearance. During -the fall and winter it is covered with scarlet berries, which in -contrast with the persistent foliage produce a pleasing effect.</p> - -<div class="footnote"> - -<p><a name="Footnote_74" id="Footnote_74"></a><a href="#FNanchor_74"><span class="label">[74]</span></a> <i>Schinus molle</i> L.</p></div> - -<div class="fig_center" style="width: 477px;"><a id="Fig_28"></a> -<img src="images/fig28.png" width="477" height="333" alt="" /> -<div class="fig_caption"><span class="smcap">Fig. 28.</span>—A pavement heaved by the roots of poplar trees.</div> -</div> - - -<h3><a id="POPLAR"></a>POPLAR.</h3> - -<p>Poplars are not desirable for street planting. Their wood is -brittle and easily broken by ordinary windstorms, and their roots -run near the surface and are likely to interfere with pavements, as -shown in <a href="#Fig_28">figure 28</a>, while those of some varieties are especially liable -to make trouble in sewers by filling them with a mass of fibrous roots -if access is once gained. Vigorous root growth is encouraged by the -moisture from a leak, and the roots ultimately find their way inside.</p> - -<p>The southern cottonwood,<a name="FNanchor_75" id="FNanchor_75"></a><a href="#Footnote_75" class="fnanchor">[75]</a> Carolina poplar, and the northern -cottonwood<a name="FNanchor_76" id="FNanchor_76"></a><a href="#Footnote_76" class="fnanchor">[76]</a> are so similar in their adaptability for street planting -purposes that they will be discussed together. They are easily -propagated, easily transplanted, are quick-growing, and where they -<span class="pagenum"><a name="Page_41" id="Page_41">« 41 »</a></span> -reach maturity under normal conditions form very large oval-headed -handsome trees, but under the artificial conditions existing in cities -it is necessary to prune them quite severely when young to remove -the long vigorous growths and make the heads more compact. This -pruning stimulates more vigorous growth, which must be removed or -they will form long branches with heavy tops, that are especially -liable to be injured by windstorms. The more they are pruned the -greater the tendency to an undesirable form of growth. They begin -dropping their leaves early in the summer and lose them very early -in the autumn. Their root growth is especially vigorous, so that -they are liable to make trouble in sewers in the manner already -mentioned. It is largely on this account that many cities prohibit -the planting of these trees. Except in regions 6, 7, or 8 or in locations -where smoke and fumes in the air prevent the growing of -other trees, they should not be planted.</p> - -<div class="footnote"> - -<p><a name="Footnote_75" id="Footnote_75"></a><a href="#FNanchor_75"><span class="label">[75]</span></a> <i>Populus deltoides</i> Marsh.</p></div> - -<div class="footnote"> - -<p><a name="Footnote_76" id="Footnote_76"></a><a href="#FNanchor_76"><span class="label">[76]</span></a> <i>Populus virginiana</i> Fouger.</p></div> - -<p>The Lombardy poplar<a name="FNanchor_77" id="FNanchor_77"></a><a href="#Footnote_77" class="fnanchor">[77]</a> is a tall columnar tree adapted for use on -very narrow streets (<a href="#Fig_14">fig. 14</a>). It is short lived in many places, due -largely to the European poplar canker, but otherwise is a satisfactory -tree for these conditions in all parts of the United States. The trees -may be planted as close together as 30 feet.</p> - -<div class="footnote"> - -<p><a name="Footnote_77" id="Footnote_77"></a><a href="#FNanchor_77"><span class="label">[77]</span></a> <i>Populus italica</i> (Du Roi) Moench.</p></div> - -<p>None of the other poplars have much to recommend them for -street planting.</p> - - -<h3><a id="RUBBER_TREE"></a>RUBBER TREE.</h3> - -<p>The rubber tree<a name="FNanchor_78" id="FNanchor_78"></a><a href="#Footnote_78" class="fnanchor">[78]</a> is a large-headed handsome evergreen, suitable -for regions 3 and 5 and the southern parts of regions 2 and 13 when -the use of an evergreen tree is warranted.</p> - -<div class="footnote"> - -<p><a name="Footnote_78" id="Footnote_78"></a><a href="#FNanchor_78"><span class="label">[78]</span></a> <i>Ficus elastica</i> Roxb.</p></div> - - -<h3><a id="SILK_OAK"></a>SILK OAK.</h3> - -<p>The silk oak,<a name="FNanchor_79" id="FNanchor_79"></a><a href="#Footnote_79" class="fnanchor">[79]</a> or Australian fern, is a large, handsome tree that -succeeds well in regions 2, 3, and 13; also in region 5 if provided -with a reasonable amount of moisture, as it stands drought remarkably -well. It is covered in early summer with orange-colored -flowers.</p> - -<div class="footnote"> - -<p><a name="Footnote_79" id="Footnote_79"></a><a href="#FNanchor_79"><span class="label">[79]</span></a> <i>Grevillea robusta</i> A. Cunn.</p></div> - - -<h3><a id="SWEET_GUM"></a>SWEET GUM.</h3> - -<p>The sweet gum<a name="FNanchor_80" id="FNanchor_80"></a><a href="#Footnote_80" class="fnanchor">[80]</a> is adapted to regions 11, 12, and 13, especially -on sandy lands. It forms an oval-headed, handsome tree with star-shaped -leaves that assume a particularly brilliant hue in the autumn. -It is better adapted to suburban conditions than to the heart of a -city. Toward the northern limits of its successful cultivation it is -difficult to transplant, while in the warmer sections of the country -it can be moved with comparative ease. It should be transplanted -only in the spring.</p> - -<div class="footnote"> - -<p><a name="Footnote_80" id="Footnote_80"></a><a href="#FNanchor_80"><span class="label">[80]</span></a> <i>Liquidambar styraciflua</i> L.</p></div> - -<p><span class="pagenum"><a name="Page_42" id="Page_42">« 42 »</a></span></p> - -<h3><a id="SYCAMORE"></a>SYCAMORE.</h3> - -<p>The sycamore<a name="FNanchor_81" id="FNanchor_81"></a><a href="#Footnote_81" class="fnanchor">[81]</a> also called the buttonwood and buttonball tree, is -a large, open, spreading, quick-growing tree native along water-courses. -It is adapted to regions 1, 2, 3, 4, 9, 10, 11, 12, and 13 -and is worth testing in regions 5, 6, 7, and 8. Its habit of shedding -its outer bark in large flakes, leaving the white new bark showing in -large patches, makes it a conspicuous tree wherever grown. The -fruits are balls 1 inch or more in diameter and are sometimes objected -to because they make dirt when falling; also the shed bark -is considered objectionable. It is such a strong-growing handsome -tree and succeeds so well under city conditions that it is being planted -more and more frequently. It will stand more pruning and shaping -than any other street tree. Without pruning it is too large for ordinary -streets unless spaced at almost double the usual planting distance, -with the trees staggered along the street instead of being -planted opposite. Its high head and open habit of growth are distinct -advantages for street planting. Its foliage, too, is a light green, -which gives an impression of airiness with the shade. It is subject -to attack by a fungus that kills the leaves while still small or partially -mutilates them, giving them an unsightly appearance. In -some places this trouble is quite serious.</p> - -<div class="footnote"> - -<p><a name="Footnote_81" id="Footnote_81"></a><a href="#FNanchor_81"><span class="label">[81]</span></a> <i>Platanus occidentalis</i> L.</p></div> - -<p>The California sycamore<a name="FNanchor_82" id="FNanchor_82"></a><a href="#Footnote_82" class="fnanchor">[82]</a> is a native of California adapted to -regions 1, 2, 3, and 4 and portions of region 5. It is similar in general -characteristics to the sycamore.</p> - -<div class="footnote"> - -<p><a name="Footnote_82" id="Footnote_82"></a><a href="#FNanchor_82"><span class="label">[82]</span></a> <i>Platanus racemosa</i> Nutt.</p></div> - -<p>The London plane tree<a name="FNanchor_83" id="FNanchor_83"></a><a href="#Footnote_83" class="fnanchor">[83]</a> is one of the Old World forms of sycamore. -According to Alfred Render,<a name="FNanchor_84" id="FNanchor_84"></a><a href="#Footnote_84" class="fnanchor">[84]</a> "the true oriental plane is rare in -cultivation, the tree usually planted under this name being <i>Platanus -acerifolia</i>" It it more compact in habit of growth and has the -other good qualities of the sycamore. It is being more and more -used on city streets and is proving satisfactory in regions 1, 2, 3, 4, -9, 10, 11, and 12. It will probably succeed in the warmer parts of -regions 6 and 7 and also in regions 5 and 8. It is a more desirable -tree for ordinary use than the sycamore, on account of its more -compact habit and comparative freedom from disease, though it is -tender in the northernmost sections.</p> - -<div class="footnote"> - -<p><a name="Footnote_83" id="Footnote_83"></a><a href="#FNanchor_83"><span class="label">[83]</span></a> <i>Platanus acerifolia</i> (Ait.) Willd.</p></div> - -<div class="footnote"> - -<p><a name="Footnote_84" id="Footnote_84"></a><a href="#FNanchor_84"><span class="label">[84]</span></a> Bailey, L. H., ed. New York, 1916. Standard Cyclopedia of Horticulture, v. 5, p. 2707.</p></div> - - -<h3><a id="TULIP_TREE"></a>TULIP TREE.</h3> - -<p>The tulip tree<a name="FNanchor_85" id="FNanchor_85"></a><a href="#Footnote_85" class="fnanchor">[85]</a> is also sometimes called the tulip poplar or yellow -poplar, though the latter names are unfortunate, as the tree is not a -poplar or even closely related to the poplars. It is a large, rapid-growing -tree suitable for suburban conditions in regions 1, 2, 10, 11, -<span class="pagenum"><a name="Page_43" id="Page_43">« 43 »</a></span> -and 12. The leaves are of unusual form, the upper half appearing -to have been cut away, leaving a notch about where it would seem -the middle of the leaf should be. The color is a light green. The -roots are unusually soft and tender, and therefore the tree needs to -be transplanted quickly and with great care. Small sizes should be -planted, especially near the northern limits of growth. It should be -transplanted only in the spring. If after transplanting it the top -should die and a new vigorous shoot should put out from the root, it -would be desirable to form a new top from this shoot rather than to -transplant another tree.</p> - -<div class="footnote"> - -<p><a name="Footnote_85" id="Footnote_85"></a><a href="#FNanchor_85"><span class="label">[85]</span></a> <i>Liriodendron tulipifera</i> L.</p></div> - - -<hr class="chap" /> - - - -<h2><a name="CULTURE_OF_STREET_TREES" id="CULTURE_OF_STREET_TREES">CULTURE OF STREET TREES.</a></h2> - - -<h3><a id="SELECTION_OF_INDIVIDUAL_TREES"></a>SELECTION OF INDIVIDUAL TREES.</h3> - -<p>Nursery-grown trees should be used for street planting, and they -should have been transplanted at least every two years while in the -nursery. This is to insure a thorough root pruning and the production -of numerous fibrous roots close to the trunk. Trees not frequently -transplanted form a few long roots that are largely cut off -when the tree is dug. Trees growing in the woods form a few very -long roots, and when an attempt is made to dig them only a little of -the root next the trunk is obtained, while most of the roots, including -the fibrous ones, are left in the ground. If woodland trees are -wanted for street purposes, most kinds should be grown for a few -years in a nursery in order to form a good root system before being -planted on the streets.</p> - -<p>In addition to a good root system, the tree should have a straight -trunk for the variety, with a good set of branches, called the head, the -bottom branches being from 7 to 9 feet from the ground. Trees -which naturally head low should be started with a higher head than -those varieties that have a tendency to an upright growth. A good -head for a shade tree is a leader or upright branch with three or more -side branches about equally spaced around the tree. The trees -should be healthy, free from scars, and also free from evidences of -insects or diseases. In the presence of insects, trees should be thoroughly -fumigated along approved methods before leaving nurseries, -to insure against the introduction and distribution of pests. Weakened -vitality resulting from transplanting and subsequent neglect -will frequently invite attack by bark-boring insects which seriously -damage or kill the trees. Mulching and watering will often prevent -this damage.</p> - -<p>Opinion as to the size to plant differs somewhat, but for average -conditions trees from 10 to 12 feet high and with trunks or stems -from 2 to 2<sup>1</sup>/<sub>2</sub> inches in diameter<a name="FNanchor_86" id="FNanchor_86"></a><a href="#Footnote_86" class="fnanchor">[86]</a> are very satisfactory in most<span class="pagenum"><a name="Page_44" id="Page_44">« 44 »</a></span> -varieties used for street purposes. With such varieties as elms -sycamores, and some southern oaks, somewhat larger trees can be -used equally well, while smaller trees would be better in the regions -of limited rainfall both east and west of the Rocky Mountains and -for tulip trees and sweet gums, especially in the northern portion of -their range of usefulness.</p> - -<div class="footnote"> - -<p><a name="Footnote_86" id="Footnote_86"></a><a href="#FNanchor_86"><span class="label">[86]</span></a> Designated by nurserymen as "caliper."</p></div> - - -<h3><a id="PREPARATION_OF_HOLES"></a>PREPARATION OF HOLES.</h3> - -<p>Next to the selection of a proper variety, the preparation of the hole -is the most important detail of street tree planting. Because of the -restricted area available for the spread of the tree roots, and owing to -the artificial conditions imposed by the improvement of city streets, -the soil provided for the feeding ground of the roots of the young tree -must be liberal in quantity and of the best quality. From 2 to 3 -cubic yards of soil should be provided for each tree. It is desirable to -have at least 18 square feet of opening in the sidewalk, especially if -it is of concrete or other impervious material. Trees will grow with -smaller sidewalk openings, but they are not likely to thrive so well, -and it is impossible properly to prepare a hole for planting a tree without -disturbing at least this much surface soil. The proper depth of -soil is from 2<sup>1</sup>/<sub>2</sub> to 3 feet. A hole 3 feet deep large enough to hold 2 -cubic yards of soil has a surface area of 18 square feet. A hole -6 feet long, 3 feet wide, and 3 feet deep will hold 2 cubic yards of soil, -will have the smallest desirable surface area, and will be of such -dimensions as will best conform to the usual sidewalk and roadway -widths and thus not interfere with traffic.</p> - -<p>The tree hole must be so drained that water will not stand in it. -If the soil is so impervious as to hold water some artificial drainage -must be provided. That portion of the depth of a hole that acts as a -cistern for holding water is valueless as a feeding ground for roots. -For every cubic foot of soil in the bottom of a hole that might thus -be made valueless by standing water, 1<sup>1</sup>/<sub>2</sub> cubic feet of soil should be -added by increasing the length or width of it. Under no circumstances, -however, should the depth of available feeding ground be -less than 2 feet. The deeper the roots may be encouraged to grow, -the less injury is likely to be experienced from drought.</p> - -<p>The soil used should be topsoil from land that has been producing -good crops. This should be well enriched with rotted manure, one -part of manure to four of soil. The addition of such fertilizers as -ground bone, tankage, fish scrap, or cottonseed meal at the rate of -1 pound to the cubic yard of soil is also helpful. Commercial fertilizers -containing mostly phosphoric acid obtained from other substances -than ground bone are not to be recommended for use in the -soil about the roots at planting time. When used they should form -a surface application, worked into the soil after planting.</p> - -<p><span class="pagenum"><a name="Page_45" id="Page_45">« 45 »</a></span></p> - - -<h3><a id="PLANTING"></a>PLANTING.</h3> - -<div class="fig_right" style="width: 254px;"><a id="Fig_29"></a> -<img src="images/fig29.png" width="254" height="156" alt="" /> -<div class="phnum">P20370HP</div> - -<div class="fig_caption"><span class="smcap">Fig. 29.</span>—Trees properly "heeled in."</div> -</div> - -<p>If trees are shipped from a distance they should be taken at once on -arrival to some point where the roots may be carefully covered with -soil; there they should be unpacked and plenty of loose moist earth -worked thoroughly around and over the roots as fast as they are taken -from the box. This temporary -covering of the roots is called -"heeling in." (<a href="#Fig_29">fig. 29</a>) The -tops may be either erect or laid -almost on the ground in successive -rows, the tops of one row -lying over the roots of the previous -rows, the object being to -cover the roots thoroughly and -keep them moist until the tree -is wanted for permanent setting. -Not a moment of exposure should be permitted between the box and -the soil. If the roots appear dry, they may be dipped for a few minutes -before "heeling in" in a tub of water or in thin mud.</p> - -<div class="fig_center" style="width: 479px;"><a id="Fig_30"></a> -<img src="images/fig30.png" width="479" height="318" alt="" /> -<div class="phnum">P20000HP</div> - -<div class="fig_caption"><span class="smcap">Fig. 30.</span>—Trees handled -in a careless manner. The roots should have been covered with wet canvas.</div> -</div> - -<p>Trees in large quantities are often packed directly in cars with a -small quantity of straw about the roots. When shipped in this way -extra care (compare figs. <a href="#Fig_30">30</a> and <a href="#Fig_31">31</a>) must be exercised in taking the -trees to the point where they are to be heeled in. The wagon in -which they are to be hauled should have a tight box, and wet canvas -should be tied tightly over the load. The last is important, so that -there may be no chance for the roots to dry.</p> - -<p><span class="pagenum"><a name="Page_46" id="Page_46">« 46 »</a></span></p> - -<p>When taking trees from the ground where they have been heeled -in to the place for planting, great care must also be exercised to see -that the roots are not exposed to sun or wind, but are kept closely -covered with moss, wet burlap, or canvas until planted. Lack of -care in this matter is a greater cause of loss in tree planting than carelessness -in any other particular. One city that has its own nursery -and uses largely trees that are supposed to be difficult to move, but -is careful about not exposing the roots for a moment (<a href="#Fig_31">fig. 31</a>), has a loss -of less than 1 per cent. If the roots once dry the trees will die, and -it takes but a short exposure to dry the roots. The holes should be -prepared well in advance of planting, so that no time will be lost -when conditions are right for putting the trees in the ground.</p> - -<div class="fig_center" style="width: 474px;"><a id="Fig_31"></a> -<img src="images/fig31.png" width="474" height="351" alt="" /> -<div class="phnum">P20350HP</div> - -<div class="fig_caption"><span class="smcap">Fig. 31.</span>—A load of trees and tree boxes. The roots are packed in wet moss and a tree is not taken -from the wagon until the planter and two shovelers are at the hole where it is to be planted.</div> -</div> - -<p>In regions 1, 10, 11, 12, and 13 (<a href="#Fig_17">fig. 17</a>) the best time for planting -deciduous street trees is the month or six weeks just preceding -freezing weather in the fall. The other desirable time for planting -is as soon after freezing weather is over in the spring as the ground -is dry enough for the mechanical operations. This should be as early -as possible, as the more opportunity there is for root growth before -warm weather forces the top into growth, the better the results are -likely to be. In regions 6, 8, and 9, where the ground freezes to a -considerable depth, spring planting is to be preferred to fall planting -unless it is possible to drench the soil thoroughly for a considerable -distance around the trees at planting time and after that to mulch -<span class="pagenum"><a name="Page_47" id="Page_47">« 47 »</a></span> -the soil thoroughly and also to protect the top from the effect of -drying winter winds. Where mice abound they may be harbored in -the mulch and may girdle the tree. This may be prevented by a -collar of wire netting about the base of the trunk or by banking the -earth about it. The death of trees at the time of transplanting is -due to the drying out of either roots or tops before opportunity is -given them to become reestablished in their new locations. This -drying may be due to improper exposure at the time of digging or -before packing (<a href="#Fig_30">fig. 30</a>), poor packing, prolonged delay in delivery, -improper handling between unpacking and planting, or the existence -of conditions conducive to excessive drying out of the plant after -setting.</p> - -<div class="fig_center" style="width: 475px;"><a id="Fig_32"></a> -<img src="images/fig32.png" width="475" height="304" alt="" /> -<div class="phnum">P14340HP</div> - -<div class="fig_caption"><span class="smcap">Fig. 32.</span>—A city nursery.</div> -</div> - -<p>The atmosphere is continually claiming a tribute of moisture from -all living plants, whether the plant is in leaf and growing or is dormant. -Growing plants, and dormant plants under normal conditions, -are able to replace this moisture by absorption through the roots. In -climates where newly planted trees may obtain sufficient soil water -to replace these losses by drying, fall planting is best. Where the -plants are unable to get sufficient winter moisture, planting would -better be done only in the spring. Where the soil freezes to a depth -greater than that to which the plant roots extend, the supply of water -is cut off from the roots and the tree will be killed by drying out -through evaporation from the top. Where winter winds are very -drying and the soil moisture is limited, evaporation from the top is -likely to be in excess of that supplied by the roots and the tree is -killed in the same way.</p> - -<p><span class="pagenum"><a name="Page_48" id="Page_48">« 48 »</a></span></p> - -<div class="fig_center" style="width: 434px;"><a id="Fig_33"></a> -<img src="images/fig33.png" width="434" height="600" alt="" /> -<div class="fig_caption"><span class="smcap">Fig. 33.</span>—Setting a tree: <i>A</i>, Measuring from the curb to get the tree in line; <i>B</i>, filling the hole: <i>C</i>, placing -the box; <i>D</i>, fastening the box.</div> -</div> - -<p>In regions normally adapted to fall planting, newly set trees may -be killed by a dry autumn followed by a dry winter with, high winds -or by a cold winter with so little snow that the ground freezes below -the roots. On the other hand, trees may often be successfully planted -in the fall where such practice is not usually successful by thoroughly -mulching the soil if freezing is the sole cause of the difficulty, or by -<span class="pagenum"><a name="Page_49" id="Page_49">« 49 »</a></span> -drenching the soil thoroughly and then mulching well if lack of -moisture and high winds are the causes of the trouble. Protection -from the wind by wrapping the trunk and large limbs with burlap or -some other protecting material is also desirable.</p> - -<p>After a liberal opening has been made in the specially prepared soil -the tree should be brought, preferably from the city's own nursery -(<a href="#Fig_32">fig. 32</a>), but if such a nursery has not been provided, then from -among the newly received trees that have been "heeled in" as already -described.</p> - -<p>If the tree has been well handled and the roots carefully protected -it is ready for setting. It is desirable to immerse the roots in a thin -mixture of clay and water just before putting it in the hole if there is -suspicion that the roots have been exposed. This can be done before -leaving the nursery or "heeling in" ground, but the roots must be -properly protected. Any mutilated ends of roots should be removed, -the top should be severely pruned, as described later, and the tree -should be placed in the hole in line with the other trees (<a href="#Fig_33">fig. 33, <i>A</i></a>) -and at such a height that after the filling is completed it will be about -an inch deeper in the ground than it was before transplanting. The -roots should be spread out in as near their original position as practicable, -and soil should be carefully worked in about them with the -fingers, so that each rootlet may come in contact with soil and not -be crowded against other rootlets. When all the roots have been -placed and covered the soil should be thoroughly trampled or tamped -to bring the roots into as close contact as possible with it. Then -more soil should be put in and the ground again tamped. Of course, -in order to get satisfactory results the soil used for planting must not -be too wet or too dry. If the soil is in such a state as to hold together -in soggy masses and not spring apart again when squeezed in the -hand, it is too wet for planting. If the soil is too dry, it will not stay -in contact with the roots during the planting operations. A soil -that is too dry may be well-watered a day or two in advance of the -planting, or if excessive dryness does not make it difficult to handle, -the tree may be planted and then be thoroughly watered. After the -watering 3 or 4 inches of loose soil should be spread over the wet -ground in order to prevent undue evaporation. It should not be -trampled or pounded in any way after the water is applied. If trees -planted in moist retentive soils are watered after planting they should -be provided with a mulch of similar earth. East of the Missouri -River trees planted in soil that is in good condition usually do not -need watering at the time of planting.</p> - -<p>Trees planted from pots, cans, or boxes should have the ball of -earth taken from the receptacle handled with care, so as not to -break it further than to loosen some of the roots on the outside of -the ball; then the soil should be as carefully placed about this ball -<span class="pagenum"><a name="Page_50" id="Page_50">« 50 »</a></span> -and the loosened roots as about the roots of trees without balls. -Trees planted with balls need no root pruning and little top pruning.</p> - -<div class="fig_left" style="width: 221px;"><a id="Fig_34"></a> -<img src="images/fig34.png" width="221" height="472" alt="" /> -<div class="phnum">P20367HP</div> - -<div class="fig_caption"><span class="smcap">Fig. 34.</span>—A pin oak trimmed for planting. -Note the bad stubs (<i>A, A</i>) on the left-hand -side of the tree.</div> -</div> - -<div class="fig_right" style="width: 255px;"><a id="Fig_35"></a> -<img src="images/fig35.png" width="255" height="453" alt="" /> -<div class="phnum">P20368HP</div> - -<div class="fig_caption"><span class="smcap">Fig. 35.</span>—A sycamore trimmed for planting. Well -primed, without bad stubs.</div> -</div> - - -<h3><a id="PRUNING"></a>PRUNING.</h3> - -<p>At planting time the trees should be so pruned as to remove from -one-half to three-fourths of the leaf buds. The head should be -formed in the nursery, so that at planting time the only problem is -how to reduce the amount of prospective growth the first season -without destroying the form of the head. Specific directions are -difficult, because different species of trees are so different in their -character of growth. A species that is naturally compact in growth -(<a href="#Fig_34">fig. 34</a>) should be pruned by removing whole branches rather than -by having the ends of branches removed. One that is open and -spreading (<a href="#Fig_35">fig. 35</a>) will probably need the shortening of the longer -limbs as well as the removal of interior branches. The first pruning -<span class="pagenum"><a name="Page_51" id="Page_51">« 51 »</a></span> -should be the removal of such branches as can be spared. If enough -buds can not be removed in this way without leaving the head too -open, then the shortening of the branches must follow. It is usually -necessary to remove three-fourths of the limbs to accomplish this. -An expert can do this pruning or most of it more easily before the -tree is planted than afterwards. Some additional pruning may be -necessary after the tree is set.</p> - -<p>In addition to the pruning of the top the roots may need some -cutting. Any broken pieces or ends should be removed, making a -clean cut with a sharp knife, as new rootlets put out more readily -from a cleanly cut fresh surface than from ragged breaks. If the -roots are very long, without branches or rootlets, it sometimes makes -planting easier to cut off some of the ends. As roots are the braces -by which a tree is supported in the ground, it is undesirable to -reduce their length unless some positive good is to be gained by it.</p> - -<div class="fig_center" style="width: 479px;"><a id="Fig_36"></a> -<img src="images/fig36.png" width="479" height="227" alt="" /> -<div class="phnum">P20372HP</div> - -<div class="fig_caption"><span class="smcap">Fig. 36.</span>—Types of tree guards.</div> -</div> - -<p>The best implement for cutting small limbs is a sharp knife, and -for larger limbs a fine-toothed saw. Pruning shears are sometimes -used, but they are likely to bruise the wood. If used at all, the -blade should always be turned toward the tree so that the bruise -made by the supporting bar will be on the portion cut off. Where -branches are taken off, the cut should be close to the remaining -limb, so that no suggestion of a stub will remain. (Figs. <a href="#Fig_34">34</a> and <a href="#Fig_35">35</a>.) -Where ends are cut from branches the cut should be just above a -bud, and the remaining bud should point in the direction that it is -desired the limb should grow.</p> - - -<h3><a id="STAKES_AND_GUARDS"></a>STAKES AND GUARDS.</h3> - -<p>Under city conditions young trees need the support of a strong -stake as well as protection for the trunk. Boys like to swing around -small trees or see the tops fly up if bent to the ground. Men find -them convenient hitching posts for their horses, and horses frequently -<span class="pagenum"><a name="Page_52" id="Page_52">« 52 »</a></span> -like the taste of the bark or tear it off for the sake of having something -to do.</p> - -<p>Guards are of many forms (<a href="#Fig_36">fig. 36</a>), from stakes 2<sup>1</sup>/<sub>2</sub> inches square -set 3 feet in the ground and extending 6 feet above, with heavy-netting -placed about the tree and stapled to the stake, to heavy -wooden cribs of four stakes and intermediate slats and wrought-iron -patterns of many forms.</p> - -<p>The trees should be firmly secured to the tops of the guards so -that they will not swing against them in the wind and be rubbed. -This is best done by securing the tree in place in the guard by two -loops of pieces of old garden hose, soft leather, or rope, in such a -way as not to bind the tree too tightly while keeping it from swinging -much or rubbing. The essentials are a firm support for the tree -while young with reasonable protection of the trunk from careless -depredations until the tree has reached a diameter of 6 inches or -more.</p> - - -<h3><a id="LATER_CARE"></a>LATER CARE.</h3> - -<p>If after planting, the season is dry and it becomes necessary to -apply water, the ground should be soaked thoroughly, and as soon -as it has dried sufficiently to work up loosely it should be hoed or -raked to make a good earth mulch. A mulch of strawy manure or -litter may be used in place of the earth mulch if desired. The -watering should not require repeating for a week or more.</p> - -<p>If the weather becomes warm soon after planting and the trees -come into leaf, wither, and droop, further pruning may save them. -The reason for the difficulty is probably that the growth of the top -has been greater than the newly formed roots can support; therefore -the additional pruning is likely to restore the balance between the -top growth and root growth. At least three-fourths of the remaining -young wood should be removed. This may leave the tree looking -almost like a bean pole, but if it induces a vigorous root growth -the top can easily be re-formed.</p> - -<p>Young trees should have an annual inspection, and all crossing -branches and any that are not well placed to form a good head -should be removed. Attention should be given also to all forks, -and where two branches start almost parallel to one another or at a -small angle, making a fork liable to split apart as the tree grows, -one branch should be removed. Where three branches start from -almost the same point there is little likelihood of their splitting apart, -but with only two growing at a less angle than 30° there is liable -to be trouble in the case of most kinds of trees. On trees on which -few but long shoots form, it may be well to remove the ends of such -shoots. As a rule, it is undesirable to use for street planting trees -with this kind of growth. Young trees should be trained into a -desirable shape by the use of a pruning knife each year, so that a -saw will not be necessary later. Some trees have a tendency to -<span class="pagenum"><a name="Page_53" id="Page_53">« 53 »</a></span> -form too dense a head. The interior branches of these should be -removed and the head made as open as possible while the work can -be done with a knife. No attempt should be made to alter the -natural form of a tree but only to insure its best development. A -skillfully pruned young tree will show no evidences of the pruning -after three or four years.</p> - - - -<hr class="chap" /> -<h2><a name="CARE_OF_MATURE_TREES" id="CARE_OF_MATURE_TREES">CARE OF MATURE TREES.</a></h2> - - -<h3><a id="PRUNING1"></a>PRUNING.</h3> - -<p>It is very little trouble to train a tree into a good shape by using -the pruning knife while the limbs are small, but it is usually difficult -to re-form a tree after it has grown to maturity. One who understands -tree growth, however, can often reshape the top of a neglected -tree to advantage, though many who make a business of tree trimming -know so little about it that they do more harm than good. -More mature trees have been hurt by severe pruning than have been -helped. Of course, dead or dying wood should be removed whenever -it is found, no matter what the age of the tree. This should -be done by cutting off the limb back to the nearest healthy crotch. -A limb should not be cut off square across (<a href="#Fig_21">fig. 21</a>) unless the tree -is apparently in a dying condition and the whole top is treated thus -in an attempt to save its life. In such a case, a second pruning -should follow within two years, at which time the stubs left at the -first trimming should be cut off in a proper manner near the newly -started limbs. Healthy silver maples and willows are frequently -cut in this way, but the maples in particular would better be cut down -at once than to subject the public to the dangers of the insidious -decay that almost always follows such an operation on these trees -and completes their destruction promptly.</p> - -<p>Trees that have been neglected a long time frequently have interfering -or crossing branches, or are too low headed or too densely -headed for the place where they are growing. Defects of this kind -may be at least partially remedied. The removal of limbs by cutting -them off at a crotch in such a manner that the wound is parallel with -the remaining branch (<a href="#Fig_37">fig. 37</a>) inflicts the least possible damage. -Such a wound in a healthy tree will soon heal over if the cut is made -through the slight collar or ring that is nearly always present at the -base of a branch. The closer this cut can be made to the trunk -the better the appearance when the cut is healed. The closer the -cut the larger the wound, but the difference is unimportant if the -wood is well protected until it is healed. These operations are -entirely different in purpose and result from the "heading in" or -"heading back" so often practiced under the guise of tree pruning, -either from a false notion of forming a top or for the passage of wires.</p> - -<p>Changing the form of a tree by pruning should not be attempted. -Each species has its own form or forms, and no attempt should be -<span class="pagenum"><a name="Page_54" id="Page_54">« 54 »</a></span> -made to change or distort a tree from its normal habit of growth. -Successful pruning will accentuate rather than disguise a tree's -characteristics.</p> - -<div class="fig_right" style="width: 331px;"><a id="Fig_37"></a> -<img src="images/fig37.png" width="331" height="386" alt="" /> -<div class="phnum">P20371HP</div> - -<div class="fig_caption"><span class="smcap">Fig. 37.</span>—Part of a tree trunk showing proper and improper methods -of removing old limbs. Although healing has started on the stub -(at the right) it is likely to proceed very slowly. The nearer the -cut is to the tree the larger the wound but the less conspicuous the -stub will be when healed.</div> -</div> - -<p>All cuts should be made so that no stubs or protuberances are left -to prevent quick healing. Small wounds need no after treatment if -the cut is well made. Large wounds should have the wood of the -center of the cut well protected to prevent decay until the new growth -has had an opportunity to heal over the cut. An application made to -the center of the cut -to preserve the wood -should not be permitted -to come near -the cambium layer -or inner bark, especially -of soft-wooded -trees like the tulip -and magnolia, as the -oil or other substances -contained in -the paint, tar, or -other covering may -spread to the cambium -layer and kill -it. It is well not to -make any application -within half an -inch of the outside -of the wound unless -the coating has been -thoroughly tested.</p> - -<p>Dead wood should -be entirely removed, -the cut being made -through good live -tissue. Removing such wood frequently exposes decayed cavities, -usually from bad stubs or injuries which have started decay that has -followed back to the main limbs or the trunk. The treatment of -such cavities is the province of tree surgery and is discussed in -another publication.<a name="FNanchor_87" id="FNanchor_87"></a><a href="#Footnote_87" class="fnanchor">[87]</a></p> - -<div class="footnote"> - -<p><a name="Footnote_87" id="Footnote_87"></a><a href="#FNanchor_87"><span class="label">[87]</span></a> Collins, J. F. Practical tree surgery. <i>In</i> U. S. Dept. Agr. Yearbook, 1913, pp. 163-190, pl. 16-22. -Published as Yearbook Separate 622, obtainable from the Superintendent of Documents for 10 cents in coin.</p></div> - -<p>One source of trouble with a large tree that has developed with -two trunks or branches instead of three or more is the liability of their -splitting apart in the crotch. This is especially characteristic of the -elm. Careful attention to the early pruning of trees may eliminate -<span class="pagenum"><a name="Page_55" id="Page_55">« 55 »</a></span> -this defect, but when it exists in mature trees it is frequently advisable -to connect the branches by a strong chain (<a href="#Fig_18">fig. 18</a>) in order to prevent -the limbs from being torn apart.</p> - - -<h3><a id="FEEDING"></a>FEEDING.</h3> - -<p>It is difficult to do anything to stimulate the growth of street -trees after they are once started, because usually the only uncovered -area over the roots is the small opening immediately about the tree; -hence, the importance of supplying the best of soil well enriched at -the time of planting. Sometimes a stimulation is desirable, which -can be accomplished by dissolving one-half to 1 pound of nitrate of -soda in 50 gallons of water and applying from 1 to 25 gallons of the -liquid, depending on the size of the tree. Unless the soil is damp at -the time of application water will be needed immediately afterward. -This material should be applied only when the tree is in full leaf and -growing. If applied when the tree is dormant it is likely to be -leached from the soil before it is absorbed. If applied late in the -season, that is, within three months of freezing weather, it would -likely stimulate a late growth that would be liable to be killed the -following winter and might make the whole tree more susceptible -to injury from cold.</p> - -<p>Water is one of the great needs of city trees, as the ground surface -is often almost completely roofed over with water-tight coverings. -It is usually a help for the pavement washings to drain into the parking -space where the tree is planted. If a curb is placed about the parking -space, frequent, regular watering is necessary where the ground is -thoroughly covered with water-tight pavements.</p> - -<p>Where growing under suburban conditions, that is, with streets -partially pervious to water, liberal parking spaces, and adjoining -lawns, street trees will respond to all extra care given the near-by -open spaces, whether parkings, lawns, or gardens. If these are well -cared for the trees should have ample sustenance from them without -any direct applications.</p> - -<p>In order to prevent the soil about a tree from being packed too -hard by trampling it is frequently desirable on business streets to -cover the soil about it with an iron grating.</p> - - -<h3><a id="SPRAYING"></a>SPRAYING.</h3> - -<p>Street trees, like all other forms of vegetation, are subject to attacks -of insects and diseases. Because of the unfavorable conditions under -which they grow, spraying for biting and sucking insects and suitable -treatment for borers or other burrowing insects require especially -careful attention.</p> - -<p>In addition to a number of troubles common to street trees in general, -each species is liable to troubles of its own; hence, the need of -competent supervision by a trained man with an efficient outfit -rather than leaving; the work to individual initiative.</p> - -<p><span class="pagenum"><a name="Page_56" id="Page_56">« 56 »</a></span></p> - -<p>Because of the height which many street trees attain a powerful -outfit is required to spray them properly. One capable of maintaining -a pressure of 200 pounds per square inch is desirable. The type -of spray required for tall trees is different from that used on fruit -trees and other low plants. For low trees the ideal spray is a mist -within a few feet of the nozzle, application being accomplished by -having the nozzles near the foliage to be treated. For tall trees it is -desirable that the liquid should leave the nozzle in a solid stream, -which is broken into spray as it passes through the air. The material -has to be projected with sufficient force to reach the highest trees -before being entirely converted into mist, as it is impracticable to -extend the nozzles into the trees to reach the farthest portions, as is -done with fruit and other low trees. The spray can not be applied -as uniformly as a mist, but it is impracticable to climb into the -tops of shade trees to cover every part with a cloudlike spray. On -the other hand, the mist spray is better for small trees, as much -injury may be done to low trees or to the lower branches of high trees -by the force of the stream from high-pressure outfits.</p> - -<p>It is estimated that in practice up to 95 per cent of the attacking -insects can be killed with insecticides carefully applied by the stream -method under high pressure.</p> - -<p>In addition to the mechanical problem of satisfactorily covering -high trees with insecticides or fungicides there is the problem of -selecting materials that will be effective against the insects and diseases -and at the same time will not disfigure the paint or stone work -of adjacent buildings with which the materials must inevitably -come in contact in street tree spraying. It frequently happens that -the most effective remedies must be rejected because of the damage -they would do to buildings and that less efficient materials must be -used.</p> - -<p>Whitewashing the trunks of trees is a useless and unsightly practice—useless, -as it does not prevent the attacks of insects, and -unsightly, because it makes the trunks of the trees obtrusive when -they should be inconspicuous.</p> - -<p>Banding with cotton or proprietary preparations may occasionally -be useful, but because such applications are so seldom helpful and -because some of the preparations result in injury due to constriction -of the trunks, it should not be resorted to except upon special -recommendation of an entomologist familiar with the existing -conditions.</p> - -<p>Details as to enemies to be expected, methods of treatment, and -materials to be used may be found in other publications<a name="FNanchor_88" id="FNanchor_88"></a><a href="#Footnote_88" class="fnanchor">[88]</a> or may be -obtained by correspondence with the nearest State agricultural experiment -station or with the United States Department of Agriculture.</p> - -<div class="footnote"> - -<p><a name="Footnote_88" id="Footnote_88"></a><a href="#FNanchor_88"><span class="label">[88]</span></a> See list on following pages.</p> - -<p><span class="pagenum"><a name="Page_57" id="Page_57">« 57 »</a></span></p> -</div> - - - -<hr class="tb" /> - -<p class="caption2">PUBLICATIONS OF THE UNITED STATES DEPARTMENT OF AGRICULTURE -RELATING TO DISEASES AND INSECTS AFFECTING SHADE AND ORNAMENTAL TREES.</p> - -<p class="caption3">AVAILABLE FOR FREE DISTRIBUTION.</p> - - -<div class="blockquot"> - -<p>Control of Root-Knot. (Farmers' Bulletin 648.)</p> - -<p>The San Jose Scale and Its Control. (Farmers' Bulletin 650.)</p> - -<p>The Bagworm, an Injurious Shade-Tree Insect. (Farmers' Bulletin -701.)</p> - -<p>The Catalpa Sphinx. (Farmers' Bulletin 705.)</p> - -<p>The Leopard Moth: A Dangerous Imported Enemy of Shade Trees. -(Farmers' Bulletin 708.)</p> - -<p>The Oyster-Shell Scale and the Scurfy Scale. (Farmers' Bulletin -723.)</p> - -<p>The White-Pine Blister Rust. (Farmers' Bulletin 742.)</p> - -<p>Carbon Disulphid as an Insecticide. (Farmers' Bulletin 799.)</p> - -<p>The Gipsy Moth and the Brown-Tail Moth and Their Control. (Farmers' -Bulletin 845.)</p> - -<p>Common White Grubs. (Farmers' Bulletin 940.)</p> - -<p>The Blights of Coniferous Nursery Stock. (Department Bulletin 44.)</p> - -<p>Forest Disease Surveys. (Department Bulletin 658.)</p></div> - -<p class="caption3">FOR SALE BY THE SUPERINTENDENT OF DOCUMENTS,<br /> -GOVERNMENT PRINTING OFFICE, WASHINGTON, D. C.</p> - -<div class="blockquot"> - -<p>The Mistletoe Pest in the Southwest. (Bureau of Plant Industry -Bulletin 166.) Price, 10 cents.</p> - -<p>The Death of Chestnuts and Oaks Due to Armillaria mellea. -(Department Bulletin 89.) Price, 5 cents.</p> - -<p>New Facts Concerning the White-Pine Blister Rust. (Department -Bulletin 116.) Price, 5 cents.</p> - -<p>The Huisache Girdler. (Department Bulletin 184.) Price, 5 cents.</p> - -<p>Report on the Gipsy Moth Work in New England. (Department Bulletin -204.) Price, 30 cents.</p> - -<p>A Disease of Pines Caused by Cronartium pyriforme. (Department -Bulletin 247.) Price, 5 cents.</p> - -<p>Food Plants of the Gipsy Moth in America. (Department Bulletin -250.) Price, 10 cents.</p> - -<p>Dispersion of Gipsy Moth Larvę by the Wind. (Department Bulletin -273.) Price, 15 cents.</p> - -<p>The Cottonwood Borer. (Department Bulletin 424.) Price, 5 cents.</p> - -<p>Solid-Stream Spraying against the Gipsy Moth and the Brown-Tail -Moth in New England. (Department Bulletin 4.80.) Price, 15 cents.</p> - -<p>Protection from the Locust Borer. (Department Bulletin 787.) Price, -5 cents.</p> - -<p>Principal Insects Liable to be Distributed on Nursery Stock. -(Entomology Bulletin 34, n. s.) Price, 5 cents.</p> - -<p>The Locust Borer. (Entomology Bulletin 58, part 1.) Price, 5 cents.</p> - -<p>Additional Data on the Locust Borer. (Entomology Bulletin 58, part -3.) Price, 5 cents.</p> - -<p>The San Jose or Chinese Scale. (Entomology Bulletin 62.) Price, 25 -cents.</p> - -<p>Report on Field Work against the Gipsy Moth and the Brown-Tail -Moth. (Entomology Bulletin 87.) Price, 35 cents.</p> -<span class="pagenum"><a name="Page_58" id="Page_58">« 58 »</a></span> -<p>The Importation into the United States of the Parasites of the -Gipsy Moth and the Brown-Tail Moth. (Entomology Bulletin 91.) -Price, 65 cents.</p> - -<p>The Dispersion of the Gipsy Moth. (Entomology Bulletin 119.) Price, -20 cents.</p> - -<p>The Green-Striped Maple Worm. (Entomology Circular 110.) Price, 5 -cents.</p> - -<p>The Oak Pruner. (Entomology Circular 130.) Price, 5 cents.</p> - -<p>The Dying Hickory Trees: Cause and Remedy. (Entomology Circular -144.) Price, 5 cents.</p> - -<p>Flour Paste as a Control for Red Spiders and as a Spreader for -Contact Insecticides. (Entomology Circular 166.) Price, 5 cents.</p> - -<p>Three Undescribed Heart-Rots of Hardwood Trees, Especially of Oak. -(Journal of Agricultural Research, vol. 1, No. 2.) Price, 25 -cents.</p> - -<p>A Serious Disease in Forest Nurseries Caused by Peridermium -filamentosum. (Journal of Agricultural Research, vol. v, No. -17.) Price, 10 cents.</p> - -<p>The Chestnut Bark Disease. (Separate 598, from Yearbook of the -Department of Agriculture for 1918.) Price, 10 cents.</p> - -<p>Practical Tree Surgery. (Separate 622, from Yearbook of the -Department of Agriculture for 1913.) Price, 10 cents.</p> - -<p>Forest Tree Diseases Common in California and Nevada. (Forest -Service Unnumbered Publication.) Price, 25 cents.</p></div> - - -<p class="center double"> -ADDITIONAL COPIES<br /> -<span class="smaller">OF THIS PUBLICATION MAY BE PROCURED FROM<br /> -THE SUPERINTENDENT OF DOCUMENTS<br /> -GOVERNMENT PRINTING OFFICE<br /> -WASHINGTON, D. C.<br /> -AT<br /> -15 CENTS PER COPY</span><br /> -</p> - - - -<hr class="tb" /> - - -<div class="trans_notes"> -<p>Transcriber Notes</p> - - -<p>Illustrations were moved so as to not split paragraphs.</p> - -</div> - - - - - - - - - - -<pre> - - - - - -End of the Project Gutenberg EBook of USDA Bulletin No. 816, by F. L. 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