STUDIES OF TREES
BY J.J. LEVISON, M.F. Lecturer on Ornamental and Shade Trees, Yale University Forest School; Forester to the Department of Parks, Brooklyn, N.Y.
FIRST EDITION FIRST THOUSAND
In presenting this volume, the author is aware that there are several excellent books, dealing with one phase or another of tree life, already before the public. It is believed, however, that there is still need for an all-round book, adapted to the beginner, which gives in a brief and not too technical way the most important facts concerning the identification, structure and uses of our more common trees, and which considers their habits, enemies and care both when growing alone and when growing in groups or forests.
In the chapters on the identification of trees, the aim has been to bring before the student only such characters and facts as shall help him to distinguish the tree readily during all seasons of the year. Special stress is laid in each case on the most striking peculiarities. Possible confusion with other trees of similar appearance is prevented as far as possible through comparisons with trees of like form or habit.
Only such information is given concerning the structure and requirements of trees as will enable the reader better to understand the subsequent chapters. In the second half of the book, practical application is made of the student's general knowledge thus acquired, and he is acquainted with the fundamental principles of planting, care, forestry, wood identification and nature study.
The author recognizes the vastness of the field he is attempting to cover and the impossibility of even touching, in a small hand-book of this character, on every phase of tree study. He presumes no further; yet he hopes that by adhering to what is salient and by eliminating the less important, though possibly interesting, facts, he is able to offer a general and elementary resume of the whole subject of value to students, private owners, farmers and teachers.
In the preparation of Chapter VIII on "Our Common Woods: Their Identification, Properties and Uses," considerable aid has been received from Prof. Samuel J. Record, author of "Economic Woods of the United States." Acknowledgment is also due to the U.S. Forest Service for the photographs used in Figs. 18, 122 to 138 inclusive and 142; to Dr. George B. Sudworth, Dendrologist of the U.S. Forest Service, for checking up the nomenclature in the lists of trees under Chapter V; to Dr. E.P. Felt, Entomologist of the State of New York, for suggestions in the preparation of the section of the book relating to insects; to Dr. W.A. Murrill, Assistant Director of the New York Botanical Gardens, for Fig. 108; and to Mr. Hermann W. Merkel, Chief Forester of the New York Zoological Park, for Figs. 26, 59 and 60.
BROOKLYN, N.Y. June, 1914.
HOW TO IDENTIFY TREES The Pines The Spruce and Hemlock The Red Cedar and Arbor-vitae
HOW TO IDENTIFY TREES (Continued) The Larch and Cypress The Horsechestnut, Ash, and Maple Trees Told by their Form Trees Told by their Bark or Trunk The Oaks and Chestnut
HOW TO IDENTIFY TREES (Continued) The Hickories, Walnut, and Butternut Tulip Tree, Sweet Gum, Linden, Magnolia, Locust, Catalpa, Dogwood, Mulberry, and Osage Orange
THE STRUCTURE AND REQUIREMENTS OF TREES
WHAT TREES TO PLANT AND HOW Trees for the Lawn Trees for the Street Trees for Woodland Trees for Screening
THE CARE OF TREES Insects Injurious to Trees and How to Combat Them Important Insects Tree Diseases Pruning Trees Tree Repair
FORESTRY What Forestry Is and What It Does Care of the Woodland
OUR COMMON WOODS: THEIR IDENTIFICATION, PROPERTIES AND USES Woods Without Pores (Soft woods) Woods with Pores (Hard woods)
AN OUTDOOR LESSON ON TREES
A good many popular books on trees have been published in the United States in recent years. The continually increasing demand for books of this character indicates the growing public interest not only in the trees that we pass in our daily walks, but also in the forest considered as a community of trees, because of its aesthetic and protective value and its usefulness as a source of important economic products.
As a nation, we are thinking more about trees and woods than we were wont to do in the years gone by. We are growing to love the trees and forests as we turn more and more to outdoor life for recreation and sport. In our ramblings along shady streets, through grassy parks, over wooded valleys, and in mountain wildernesses we find that much more than formerly we are asking ourselves what are these trees, what are the leaf, flower, twig, wood and habit characteristics which distinguish them from other trees; how large do they grow; under what conditions of soil and climate do they thrive best; what are their enemies and how can they be overcome; what is their value for wood and other useful products; what is their protective value; are they useful for planting along streets and in parks and in regenerating forests; how can the trees of our streets and lawns be preserved and repaired as they begin to fail from old age or other causes? All these questions and many more relating to the important native and exotic trees commonly found in the states east of the Great Lakes and north of Maryland Mr. Levison has briefly answered in this book. The author's training as a forester and his experience as a professional arboriculturist has peculiarly fitted him to speak in an authoritative and interesting way about trees and woods.
The value of this book is not in new knowledge, but in the simple statement of the most important facts relating to some of our common trees, individually and collectively considered. A knowledge of trees and forests adds vastly to the pleasures of outdoor life. The more we study trees and the more intimate our knowledge of the forest as a unit of vegetation in which each tree, each flower, each animal and insect has its part to play in the complete structure, the greater will be our admiration of the wonderful beauty and variety exhibited in the trees and woods about us.
J.W. TOUMEY, Director, Yale University Forest School.
NEW HAVEN, CONN., June, 1914.
STUDIES OF TREES
HOW TO IDENTIFY TREES
There are many ways in which the problem of identifying trees may be approached. The majority attempt to recognize trees by their leaf characters. Leaf characters, however, do not differentiate the trees during the other half of the year when they are bare. In this chapter the characterizations are based, as far as possible, on peculiarities that are evident all year round. In almost every tree there is some one trait that marks its individuality and separates it, at a glance, from all other trees. It may be the general form of the tree, its mode of branching, bark, bud or fruit. It may be some variation in color, or, in case of the evergreen trees, it may be the number and position of the needles or leaves. The species included in the following pages have thus been arranged in groups based on these permanent characters. The individual species are further described by a distinguishing paragraph in which the main character of the tree is emphasized in heavy type.
The last paragraph under each species is also important because it classifies all related species and distinguishes those that are liable to be confused with the particular tree under consideration.
GROUP I. THE PINES
How to tell them from other trees: The pines belong to the coniferous class of trees; that is, trees which bear cones. The pines may be told from the other coniferous trees by their leaves, which are in the form of needles two inches or more in length. These needles keep green throughout the entire year. This is characteristic of all coniferous trees, except the larch and cypress, which shed their leaves in winter.
The pines are widely distributed throughout the Northern Hemisphere, and include about 80 distinct species with over 600 varieties. The species enumerated here are especially common in the eastern part of the United states, growing either native in the forest or under cultivation in the parks. The pines form a very important class of timber trees, and produce beautiful effects when planted in groups in the parks.
How to tell them from each other: The pine needles are arranged in clusters; see Fig. 1. Each species has a certain characteristic number of needles to the cluster and this fact generally provides the simplest and most direct way of distinguishing the different pines.
In the white pine there are five needles to each cluster, in the pitch pine three, and in the Scotch pine two. The Austrian pine also has two needles to the cluster, but the difference in size and character of the needles will distinguish this species from the Scotch pine.
THE WHITE PINE (Pinus strobus)
Distinguishing characters: The tree can be told at close range by the number of needles to each cluster, Fig. 2. There are *five* needles to each cluster of the white pine. They are bluish green, slender, and about four inches in length.
At a distance the tree may be told by the *right angles* which the branches form with the main trunk, Fig. 3. No other pine shows this character.
Form and size: A tall tree, the stateliest of the evergreens.
Range: Eastern North America.
Soil and location: Prefers a deep, sandy soil, but will grow in almost any soil.
Enemies: Sucking insects forming white downy patches on the bark and twigs, the white pine weevil, a boring insect, and the white pine blister rust, a fungus, are among its principal enemies.
Value for planting: Aside from its value as an ornamental tree, the white pine is an excellent tree to plant on abandoned farms and for woodlands and windbreaks throughout the New England States, New York, Pennsylvania, and the Lake States.
Commercial value: The wood is easily worked, light, durable, and will not warp. It is used for naval construction, lumber, shingles, laths, interior finish, wooden ware, etc.
Other characters: The fruit is a cone, four to six inches long.
Comparisons: The tree is apt to be confused with the Bhotan pine (Pinus excelsa), which is commonly grown as an ornamental tree. The Bhotan pine, however, has needles much longer and more drooping in appearance.
THE PITCH PINE (Pinus rigida)
Distinguishing characters: Here there are *three* needles to each cluster, Fig. 4. They are dark, yellowish-green needles about four inches long. The rough-looking branches of the tree may be seen studded with cones throughout the year, and clusters of leaves may be seen sprouting directly from the trunk of the tree; see Fig. 5. The last two are very characteristic and will distinguish the tree at a glance.
Form and size: It is a low tree of uncertain habit and extremely rough looking at every stage of its life. It is constantly full of dead branches and old cones which persist on the tree throughout the year.
Range: Eastern United States.
Soil and location: Grows in the poorest and sandiest soils where few other trees will grow. In New Jersey and on Long Island where it is native, it proves so hardy and persistent that it often forms pure stands excluding other trees.
Enemies: None of importance.
Value for planting: Well adapted for the sea coast and other exposed places. It is of extremely uncertain habit and is subject to the loss of the lower limbs. It frequently presents a certain picturesqueness of outline, but it could not be used as a specimen tree on the lawn.
Commercial value: The wood is coarse grained and is used for rough lumber, fuel, and charcoal.
Other characters: The fruit is a cone one to three inches long, persistent on the tree for several years.
THE SCOTCH PINE (Pinus sylvestris)
Distinguishing characters: There are *two* needles to each cluster, and these are short compared with those of the white pine, and slightly twisted; see Fig. 6. The bark, especially along the upper portion of the trunk, is reddish in color.
Form and size: A medium-sized tree with a short crown.
Range: Europe, Asia, and eastern United States.
Soil and location: Will do best on a deep, rich, sandy soil, but will also grow on a dry, porous soil.
Enemies: In Europe the Scotch pine has several insect enemies, but in America it appears to be free from injury.
Value for planting: Suitable for windbreaks and woodland planting. Many excellent specimens may also be found in our parks.
Commercial value: In the United States, the wood is chiefly used for fuel, though slightly used for barrels, boxes, and carpentry. In Europe, the Scotch pine is an important timber tree.
Comparisons: The Scotch pine is apt to be confused with the Austrian pine (Pinus austriaca), because they both have two needles to each cluster. The needles of the Austrian pine, however, are much longer, coarser, straighter, and darker than those of the Scotch pine; Fig. 1. The form of the Austrian pine, too, is more symmetrical and compact.
The red pine (Pinus resinosa) is another tree that has two needles to each cluster, but these are much longer than those of the Scotch pine (five to six inches) and are straighter. The bark, which is reddish in color, also differentiates the red pine from the Austrian pine. The position of the cones on the red pine, which point outward and downward at maturity, will also help to distinguish this tree from the Scotch and the Austrian varieties.
GROUP II. THE SPRUCE AND HEMLOCK
How to tell them from other trees: The spruce and hemlock belong to the evergreen class and may be told from the other trees by their leaves. The characteristic leaves of the spruce are shown in Fig. 9; those of the hemlock in Fig. 10. These are much shorter than the needles of the pines but are longer than the leaves of the red cedar or arbor vitae. They are neither arranged in clusters like those of the larch, nor in feathery layers like those of the cypress. They adhere to the tree throughout the year, while the leaves of the larch and cypress shed in the fall.
The spruces are pyramidal-shaped trees, with tall and tapering trunks, thickly covered with branches, forming a compact crown. They are widely distributed throughout the cold and temperate regions of the northern hemisphere, where they often form thick forests over extended areas.
There are eighteen recognized species of spruce. The Norway spruce has been chosen as a type for this group because it is so commonly planted in the northeastern part of the United States.
The hemlock is represented by seven species, confined to temperate North America, Japan, and Central and Western China.
How to tell them from each other: The needles and branches of the spruce are coarse; those of the hemlock are flat and graceful. The individual leaves of the spruce, Fig. 9, are four-sided and green or blue on the under side, while those of the hemlock, Fig. 10, are flat and are marked by two white lines on the under side.
THE NORWAY SPRUCE (Picea excelsa)
Distinguishing characters: The characteristic appearance of the full-grown tree is due to the *drooping branchlets* carried on *main branches which bend upward* (Fig. 7).
Leaf: The leaves are dark green in color and are arranged spirally, thus making the twigs coarser to the touch than the twigs of the hemlock or fir. In cross-section, the individual leaflet is quadrilateral, while that of the pine is triangular.
Form and size: A large tree with a straight, undivided trunk and a well-shaped, conical crown (Fig. 7).
Range: Northern Europe, Asia, northern North America.
Soil and location: Grows in cool, moist situations.
Enemies: The foliage of the spruce is sometimes affected by red spider, but is apt to be more seriously injured by drought, wind, and late frosts.
Value for planting: Commonly planted as an ornamental tree and for hedges. It does well for this purpose in a cool northern climate, but in the vicinity of New York City and further south it does not do as well, losing its lower branches at an early age, and becoming generally scraggly in appearance.
Commercial value: The wood is light and soft and is used for construction timber, paper pulp, and fuel.
Other characters: The fruit is a large slender cone, four to seven inches long.
Comparisons: The white spruce (Picea canadensis) may be told from the Norway spruce by the whitish color on the under side of its leaves and the unpleasant, pungent odor emitted from the needles when bruised. The cones of the white spruce, about two inches long, are shorter than these of the Norway spruce, but are longer than those of the black spruce.
It is essentially a northern tree growing in all sorts of locations along the streams and on rocky mountain slopes as far north as the Arctic Sea and Alaska. It often appears as an ornamental tree as far south as New York and Pennsylvania.
The black spruce (Picea mariana) may be told from the other spruces by its small cone, which is usually only about one inch in length. In New England it seldom grows to as large a size as the other spruce trees.
It covers large areas in various parts of northern North America and grows to its largest size in Manitoba. The black spruce has little value as an ornamental tree.
The Colorado blue spruce (Picea parryana or Picea pungens) which is commonly used as an ornamental tree on lawns and in parks, can be told from the other spruces by its pale-blue or sage-green color and its sharp-pointed, coarse-feeling twigs. Its small size and sharp-pointed conical form are also characteristic.
It grows to a large size in Colorado and the Middle West. In the Eastern States and in northern Europe where it is planted as an ornamental tree, it is usually much smaller.
HEMLOCK (Tsuga canadensis)
Distinguishing characters: Its leaves are arranged in *flat layers*, giving a flat, horizontal and graceful appearance to the whole branch (Fig. 8). The individual leaves are dark green above, lighter colored below, and are *marked by two white lines on the under side* (Fig. 10).
The leaves are arranged on little stalks, a characteristic that does not appear in the other evergreen trees.
Form and size: A large tree with a broad-based pyramidal head, and a trunk conspicuously tapering toward the apex. The branches extend almost to the ground.
Range: The hemlock is a northern tree, growing in Canada and the United States.
Soil and location: Grows on all sorts of soils, in the deepest woods as well as on high mountain slopes.
Enemies: None of importance.
Value for planting: The hemlock makes an excellent hedge because it retains its lowest branches and will stand shearing. In this respect it is preferable to the spruce. It makes a fair tree for the lawn and is especially desirable for underplanting in woodlands, where the shade from the surrounding trees is heavy. In this respect it is like the beech.
Commercial value: The wood is soft, brittle, and coarse-grained, and is therefore used mainly for coarse lumber. Its bark is so rich in tannin that it forms one of the chief commercial products of the tree.
Other characters: The fruit is a small cone about 3/4 of an inch long, which generally hangs on the tree all winter.
GROUP III. THE RED CEDAR AND ARBOR-VITAE
How to tell them from other trees: The red cedar (juniper) and arbor-vitae may be told from other trees by their leaves, which remain on the tree and keep green throughout the entire year. These leaves differ from those of the other evergreens in being much shorter and of a distinctive shape as shown in Figs. 12 and 13. The trees themselves are much smaller than the other evergreens enumerated in this book. Altogether, there are thirty-five species of juniper recognized and four of arbor-vitae. The junipers are widely distributed over the northern hemisphere, from the Arctic region down to Mexico in the New World, and in northern Africa, China, and Japan in the Old World. The arbor-vitae is found in northeastern and northwestern America, China, and Japan. The species mentioned here are those commonly found in America.
How to tell them from each other: The twigs of the arbor-vitae are flat and fan-like as in Fig. 13; the twigs of the red cedar are needle-shaped or scale-like as in Fig. 12. The foliage of the arbor-vitae is of a lighter color than that of the red cedar, which is sombre green. The arbor-vitae will generally be found growing in moist locations, while the red cedar will grow in dry places as well. The arbor-vitae generally retains its lower branches in open places, while the branches of the red cedar start at some distance from the ground.
RED CEDAR (Juniperus virginiana)
Distinguishing characters: The tree can best be told at a glance by its general form, size and leaves. It is a medium-sized tree with a symmetrical, cone-like form, Fig. 11, which, however, broadens out somewhat when the tree grows old. Its color throughout the year is dull green with a tinge of brownish red, and its bark peels in thin strips.
Leaf: In young trees the leaf is needle-shaped, pointed, and marked by a white line on its under side, Fig. 12(a). In older trees it is scale-like, Fig. 12(b), and the white line on its under side is indistinct.
Range: Widely distributed over nearly all of eastern and central North America.
Soil and location: Grows on poor, gravelly soils as well as in rich bottom lands.
Enemies: The "cedar apple," commonly found on this tree, represents a stage of the apple rust, and for that reason it is not desirable to plant such trees near orchards. Its wood is also sometimes attacked by small boring insects.
Value for planting: Its characteristic slender form gives the red cedar an important place as an ornamental tree, but its chief value lies in its commercial use.
Commercial value: The wood is durable, light, smooth and fragrant, and is therefore used for making lead-pencils, cabinets, boxes, moth-proof chests, shingles, posts, and telegraph poles.
Other characters: The fruit is small, round and berry-like, about the size of a pea, of dark blue color, and carries from one to four bony seeds.
Other common names: The red cedar is also often called juniper and red juniper.
Comparisons: The red cedar is apt to be confused with the low juniper (Juniperus communis) which grows in open fields all over the world. The latter, however, is generally of a low form with a flat top. Its leaves are pointed and prickly, never scale-like, and they are whitish above and green below. Its bark shreds and its fruit is a small round berry of agreeable aromatic odor.
ARBOR-VITAE; NORTHERN WHITE CEDAR (Thuja occidentalis)
Distinguishing characters: The *branchlets* are extremely *flat and fan-like*, Fig. 13, and have an agreeable aromatic odor when bruised. The tree is an evergreen with a narrow conical form.
Leaf: Leaves of two kinds, one scale-like and flat, the other keeled, all tightly pressed to the twig (see Fig. 13).
Form and size: A close, conical head with dense foliage near the base. Usually a small tree, but in some parts of the northeastern States it grows to medium size with a diameter of two feet.
Range: Northern part of North America.
Soil and location: Inhabits low, swampy lands; in the State of Maine often forming thick forests.
Enemies: Very seldom affected by insects.
Value for planting: Is hardy in New England, where it is especially used for hedges. It is also frequently used as a specimen tree on the lawn.
Commercial value: The wood is durable for posts, ties, and shingles. The bark contains considerable tannin and the juices from the tree have a medicinal value.
Other characters: The fruit is a cone about 1/2 inch long.
Other common names: Arbor-vitae is sometimes called white cedar and cedar.
Comparisons: The arbor-vitae is apt to be confused with the true white cedar (Chamaecyparis thyoides) but the leaves of the latter are sharp-pointed and not flattened or fan-shaped.
HOW TO IDENTIFY TREES—(Continued)
GROUP IV. THE LARCH AND CYPRESS
How to tell them from other trees: In summer the larch and cypress may easily be told from other trees by their leaves. These are needle-shaped and arranged in clusters with numerous leaves to each cluster in the case of the larch, and feathery and flat in the case of the cypress. In winter, when their leaves have dropped off, the trees can be told by their cones, which adhere to the branches.
There are nine recognized species of larch and two of bald cypress. The larch is characteristically a northern tree, growing in the northern and mountainous regions of the northern hemisphere from the Arctic circle to Pennsylvania in the New World, and in Central Europe, Asia, and Japan in the Old World. It forms large forests in the Alps of Switzerland and France.
The European larch and not the American is the principal species considered here, because it is being planted extensively in this country and in most respects is preferable to the American species.
The bald cypress is a southern tree of ancient origin, the well-known cypress of Montezuma in the gardens of Chepultepec having been a species of Taxodium. The tree is now confined to the swamps and river banks of the South Atlantic and Gulf States, where it often forms extensive forests to the exclusion of all other trees. In those regions along the river swamps, the trees are often submerged for several months of the year.
How to tell them from each other: In summer the larch may be told from the cypress by its leaves (compare Figs. 14 and 16). In winter the two can be distinguished by their characteristic forms. The larch is a broader tree as compared with the cypress and its form is more conical. The cypress is more slender and it is taller. The two have been grouped together in this study because they are both coniferous trees and, unlike the other Conifers, are both deciduous, their leaves falling in October.
THE EUROPEAN LARCH (Larix europaea)
Distinguishing characters: Its leaves, which are needle-shaped and about an inch long, are borne in *clusters* close to the twig, Fig. 14. There are many leaves to each cluster. This characteristic together with the *spire-like* form of the crown will distinguish the tree at a glance.
Leaf: The leaves are of a light-green color but become darker in the spring and in October turn yellow and drop off. The cypress, which is described below, is another cone-bearing tree which sheds its leaves in winter.
Form and size: A medium-sized tree with a conical head and a straight and tapering trunk. (See Fig. 90.)
Range: Central Europe and eastern and central United States.
Soil and location: Requires a deep, fresh, well-drained soil and needs plenty of light. It flourishes in places where our native species would die. Grows very rapidly.
Enemies: The larch is subject to the attacks of a sawfly, which has killed many trees of the American species. A fungus (Trametes pini) which causes the tree to break down with ease is another of its enemies.
Value for planting: A well-formed tree for the lawn. It is also useful for group planting in the forest.
Commercial value: Because its wood is strong and durable the larch is valuable for poles, posts, railroad ties, and in shipbuilding.
Other characters: The fruit is a small cone about one inch long, adhering to the tree throughout the winter.
Comparisons: The tree is apt to be confused with the American larch, also known as tamarack and hackmatack, but differs from it in having longer leaves, cones twice as large and more abundant and branches which are more pendulous.
The larch differs from the bald cypress in the broader form of its crown and the cluster-like arrangement of its leaves. The twigs of the bald cypress are flat and feathery. The larch and bald cypress have the common characteristics of both shedding their leaves in winter and preferring to grow in moist or swampy soils. The larch, especially the native species, forms the well-known tamarack swamps of the north. The bald cypress grows in a similar way in groups in the southern swamps.
BALD CYPRESS (Taxodium distichum)
Distinguishing characters: The *feathery character* of the *twigs*, Fig. 16, and the *spire-like form* of the tree, Fig. 17, which is taller and more slender than the larch, will distinguish this species from others.
Leaf: The leaves drop off in October, though the tree is of the cone-bearing kind. In this respect it is like the larch.
Form and size: Tall and pyramidal.
Range: The cypress is a southern tree, but is found under cultivation in parks and on lawns in northern United States.
Soil and location: Grows naturally in swamps, but will also do well in ordinary well-drained, good soil. In its natural habitat it sends out special roots above water. These are known as "cypress knees" (Fig. 18) and serve to provide air to the submerged roots of the tree.
Enemies: None of importance.
Value for planting: An excellent tree for park and lawn planting.
Commercial value: The wood is light, soft, and easily worked. It is used for general construction, interior finish, railroad ties, posts and cooperage.
Other characters: The bark is thin and scaly. The fruit is a cone about an inch in diameter. The general color of the tree is a dull, deep green which, however, turns orange brown in the fall.
Comparisons: The cypress and the larch are apt to be confused, especially in the winter, when the leaves of both have dropped. The cypress is more slender and is taller in form. The leaves of each are very different, as will be seen from the accompanying illustrations.
GROUP V. THE HORSECHESTNUT, ASH AND MAPLE
How to tell them from other trees: The horsechestnut, ash, and maple have their branches and buds arranged on their stems *opposite* each other as shown in Figs. 20, 22 and 24. In other trees, this arrangement is *alternate*, as shown in Fig. 19.
How to tell these three from each other. If the bud is large—an inch to an inch and a half long—dark brown, and sticky, it is a horsechestnut.
If the bud is not sticky, much smaller, and rusty brown to black in color, and the ultimate twigs, of an olive green color, are flattened at points below the buds, it is an ash.
If it is not a horsechestnut nor an ash and its small buds have many scales covering them, the specimen with branches and buds opposite must then be a maple. Each of the maples has one character which distinguishes it from all the other maples. For the sugar maple, this distinguishing character is the sharp point of the bud. For the silver maple it is the bend in the terminal twig. For the red maple it is the smooth gray-colored bark. For the Norway maple it is the reddish brown color of the full, round bud, and for the box elder it is the greenish color of its terminal twig.
The form of the tree and the leaves are also characteristic in each of the maples, but for the beginner who does not wish to be burdened with too many of these facts at one time, those just enumerated will be found most certain and most easily followed.
THE HORSECHESTNUT (Aesculus hippocastanum)
Distinguishing characters: The *sticky* nature of the *terminal bud* and its *large size* (about an inch long). The bud is dark brown in color. See Fig. 20.
Leaf: Five to seven leaflets, usually seven. Fig. 21.
Form and size: Medium-sized tree, pyramidal head and coarse twigs.
Range: Europe and eastern United States.
Soil and location: Prefers a deep, rich soil.
Enemies: The leaves are the favorite food of caterpillars and are subject to a blight which turns them brown prematurely. The trunk is often attacked by a disease which causes the flow of a slimy substance.
Value for planting: On account of its showy flowers, the horsechestnut is a favorite for the park and lawn.
Commercial value: The wood is not durable and is not used commercially.
Other characters: The flowers appear in large white clusters in May and June. The fruit is large, round, and prickly.
Comparisons: The red horsechestnut differs from this tree in having red flowers. The buckeye is similar to the horsechestnut, but its bud is not sticky and is of a lighter gray color, while the leaf generally has only five leaflets.
THE WHITE ASH (Fraxinus americana)
Distinguishing characters: The terminal *twigs* of glossy olive green color are *flattened* below the bud. Fig. 22. The bud is rusty-brown.
Leaf: Five to nine leaflets. Fig. 23.
Form and size: A large tree with a straight trunk.
Range: Eastern North America.
Soil and location: Rich, moist soil.
Enemies: In cities it is very often attacked by sucking insects.
Value for planting: The white ash grows rapidly. On account of its insect enemies in cities, it should be used more for forest planting and only occasionally for ornament.
Commercial value: It has a heavy, tough, and strong wood, which is valuable in the manufacture of cooperage stock, agricultural implements, and carriages. It is superior in value to the black ash.
Other characters: The bark is gray. The flowers appear in May.
Comparisons: The white ash is apt to be confused with the black ash (Fraxinus nigra), but differs from the latter in having a lighter-colored bud. The bud of the black ash is black. The bark of the white ash is darker in color and the terminal twigs are more flattened than those of the black ash.
SUGAR MAPLE (Acer saccharum)
Distinguishing characters: The *bud is sharp-pointed*, scaly, and reddish brown. Fig. 24.
Leaf: Has sharp points and round sinus. Fig. 25.
Form and size: The crown is oval when the tree is young and round in old age. Fig. 26.
Range: Eastern United States.
Soil and location: Moist and deep soil, and cool, shady positions.
Enemies: Subject to drouth, especially in cities. Is attacked by the sugar maple borer and the maple phenacoccus, a sucking insect.
Value for planting: Its rich and yellow color in the fall, and the fine spread of its crown make it a desirable tree for the lawn, especially in the country.
Commercial value: Its wood is hard and takes a good polish; used for interior finish and furniture. The tree is also the source of maple sugar. Fig. 27.
Other characters: The bark is smooth in young trees and in old trees it shags in large plates. The flowers appear in the early part of April.
Other common names: The sugar maple is sometimes called rock maple or hard maple.
SILVER MAPLE (Acer saccharinum)
Distinguishing characters: The tips of the *twigs curve upwards* (Fig. 28), the bark is scaly, and the leaves are very deeply cleft and are silvery on the under side.
Leaf: Deeply cleft and silvery under side. Fig. 29.
Form and size: A large tree with the main branches separating from the trunk a few feet from the ground. The terminal twigs are long, slender, and drooping.
Range: Eastern United States.
Soil and location: Moist places.
Enemies: The leopard moth, a wood-boring insect, and the cottony-maple scale, a sucking insect.
Value for planting: Grows too rapidly and is too short-lived to be durable.
Commercial value: Its wood is soft, weak, and little used.
Other characters: The bark is light gray, smooth at first and scaly later on. The scales are free at each end and attached in the center. The flowers appear before the leaves in the latter part of March or early April.
Other common names: The silver maple is sometimes known as soft maple or white maple.
RED MAPLE (Acer rubrum)
Distinguishing characters: The *bark is smooth and light gray*, like that of the beech, on the upper branches in older trees, and in young trees over the whole trunk. Fig. 30. The buds are in clusters, and the terminal twigs, Fig. 31, are quite red.
Leaf: Whitish underneath with three-pointed lobes. Fig. 32.
Form and size: A medium-sized tree with a narrow, round head.
Range: Eastern North America.
Soil and location: Prefers moist places.
Enemies: Leaf blotches (Rhytisma acerinum) which, however, are not very injurious.
Value for planting: Suitable as a shade tree for suburban streets. Its rich red leaves in the fall make it attractive for the lawn.
Commercial value: Its wood is heavy, close-grained, and takes a good polish. Used for furniture and fuel.
Other characters: The bud is small, round, and red. The flowers appear before the leaves are out in the early part of April.
Other common names: The red maple is sometimes known as swamp maple.
Comparisons: The red maple is apt to be confused with the silver maple, but the latter can be distinguished by its turned-up twigs and scaly bark over the whole trunk of the tree, which presents a sharp contrast to the straight twig and smooth bark of the red maple. The latter has a bark similar to the beech, but its branches are opposite, while those of the beech are alternate.
NORWAY MAPLE (Acer platanoides)
Distinguishing characters: The bud, Fig. 33, is *oval and reddish-brown* in color; when taken off, a *milky juice exudes*. The bark is close. Fig. 34
Leaf: Like the leaf of the sugar maple but thicker in texture and darker in color. Fig. 35.
Form and size: A tall tree with a broad, round head.
Range: Europe and the United States.
Soil and location: Will grow in poor soil.
Enemies: Very few.
Value for planting: One of the best shade trees.
Commercial value: None.
Other characters: The bark is close like that of the mockernut hickory.
Comparisons: The Norway maple is apt to be confused with the sycamore maple (Acer pseudoplatanus), but differs from the latter in having a reddish bud instead of a green bud, and a close bark instead of a scaly bark.
BOX ELDER (Acer negundo)
Distinguishing characters: The terminal *twigs are green*, and the buds are round and small. Fig. 36.
Leaf: Has three to seven leaflets.
Form and size: A medium-sized tree with a short trunk and wide-spreading top.
Range: Eastern United States to the Rocky Mountains.
Soil and location: Grows rapidly in deep, moist soil and river valleys, but accommodates itself to the dry and poor soil conditions of the city.
Value for planting: Used as a shade tree in the Middle West, but the tree is so ill formed and so short-lived that it is not to be recommended.
Commercial value: None. The wood is soft.
Other characters: The bark of the trunk is smooth and yellowish-green in young trees and grayish brown in older specimens. The flowers appear in the early part of April. The fruit takes the form of yellowish-green keys which hang on the tree till late fall.
Other common names: The box elder is also commonly known as the ash-leaf maple.
GROUP VI. TREES TOLD BY THEIR FORM: ELM, POPLAR, GINGKO AND WILLOW
How to tell them from other trees: The trees described in this group are so distinctive in their general form that they may, for the purpose of study, be grouped together, and distinguished from all other trees by this characteristic.
How to tell them from each other: The American elm is vase-like in shape; the Lombardy poplar is narrow and spire-like; the gingko, or maidenhair tree, is odd in its mode of branching; and the weeping willow is extremely pendulous.
AMERICAN ELM (Ulmus americana)
Distinguishing characters: The tree can be told at a glance by its general branching habit. The limbs arch out into a wide-spreading *fan or vase-like crown* which loses itself in numerous fine drooping branchlets. See Fig. 37.
Leaf: The leaves are simple, alternate, and from 2 to 5 inches long.
Form and size: It is a tall tree with a trunk that divides a short distance above ground. Its general contour, together with the numerous branches that interlace its massive crown, give the elm an interesting and stately appearance which is unequaled by any other tree.
Range: Eastern North America.
Soil and location: The elm prefers a deep, rich and moist soil, but will adapt itself even to the poor soil of the city street.
Enemies: The leopard moth, a wood-boring insect, and the elm leaf beetle, a leaf-eating insect, are the two most important enemies of the tree. Their ravages are very extensive.
Value for planting: The tree has a character of its own which cannot be duplicated for avenue or lawn planting.
Commercial value: The wood is strong and tough and therefore has a special value for cooperage, agricultural implements, carriages, and shipbuilding.
Other characters: The buds are small, brown, and smooth, while those of the European elms are covered with down. The small side twigs come out at almost right angles to the larger terminal twigs, which is not the case in other species of elm.
Other common names: White elm.
Comparisons: The English elm (Ulmus campestris) is also a tall, dignified tree commonly seen under cultivation in America, but may be told from the American species by the difference in their general contour. The branches of the English species spread out but do not arch like those of the American elm, and the bark of the English elm is darker and coarser, Fig. 38. Little tufts of dead twigs along the main branches and trunk of the tree are characteristic of the English elm and will frequently help to distinguish it from the American elm.
The Camperdown elm may be recognized readily by its dwarf size and its low drooping umbrella-shaped crown.
LOMBARDY OR ITALIAN POPLAR (Populus nigra, var. italica)
Distinguishing characters: Its *tall, slender, spire-like form* and rigidly *erect branches*, which commence low on the trunk, make this tree very distinct at all seasons of the year. See Fig. 39.
Leaf: Triangular in shape, similar to that of the Carolina poplar but smaller, see Fig. 40.
Range: Asia, Europe, and North America.
Soil and location: The poplar is easily grown in poor soil, in any location, and is very hardy.
Value for planting: The tree has a distinctive form which makes it valuable for special landscape effects. It is also used for shelter belts and screening. Like all poplars it is short lived and will stand pruning well.
Commercial value: None.
Comparisons: The Carolina poplar, or Cottonwood (Populus deltoides) can be told from the Lombardy poplar by its wider crown and its more open branching, Fig. 41. It may be recognized by its big terminal twigs, which are light yellow in color and coarser than those of the Lombardy poplar, Fig. 42. Its bark is smooth, light and yellowish-green in young trees, and dark gray and fissured in older specimens. Its large, conical, glossy, chestnut-brown bud is also characteristic, Fig. 42. Its flowers, in the form of large catkins, a peculiarity of all poplars, appear in the early spring. The Carolina poplar is commonly planted in cities because it grows rapidly and is able to withstand the smoke and drouth conditions of the city. Where other trees, however, can be substituted with success, the poplar should be avoided. Its very fast growth is really a point against the tree, because it grows so fast that it becomes too tall for surrounding property, and its wood being extremely soft and brittle, the tree frequently breaks in windstorms. In many cases it is entirely uprooted, because it is not a deep-rooted tree. Its larger roots, which spread near the surface, upset the sidewalk or prevent the growth of other vegetation on the lawn, while its finer rootlets, in their eager search for moisture, penetrate and clog the joints of neighboring water and sewer pipes. The tree is commonly attacked by the oyster-shell scale, an insect which sucks the sap from its bark and which readily spreads to other more valuable trees like the elm. The female form of this tree is even more objectionable than the male, because in the early spring the former produces an abundance of cotton from its seeds which litters the ground and often makes walking dangerous. The only justification for planting the Carolina poplar is in places where the conditions for tree growth are so poor that nothing else will grow, and in those cases the tree should be cut back periodically in order to keep it from becoming too tall and scraggly. It is also desirable for screening in factory districts and similar situations.
The silver or white poplar (Populus alba) may be told from the other poplars by its characteristic smooth, whitish-green bark, often spotted with dark blotches, Fig. 43. The leaves are silvery-white and downy on the under side. The twigs are dark green in color and densely covered with a white down. It grows to very large size and forms an irregular, wide-spreading, broad head, which is characteristically different from that of any of the other poplars.
The quaking aspen (Populus tremuloides), the large-toothed aspen (Populus grandidentata) and the balsam poplar or balm of Gilead (Populus balsamifera) are other common members of the poplar group. The quaking aspen may be told by its reddish-brown twigs, narrow sharp-pointed buds, and by its small finely toothed leaves. The large-toothed aspen has thicker and rather downy buds and broader and more widely toothed leaves. The balsam poplar has a large bud thickly covered with a sticky, pungent, gelatinous substance.
GINGKO OR MAIDENHAIR TREE (Gingko biloba)
Distinguishing characters: The *peculiar branches* of this tree *emerge upward* from a straight tapering trunk *at an angle of about 45 deg.* and give to the whole tree a striking, Oriental appearance, which is quite different from that of any other tree, Fig. 44.
Leaf: Like that of a leaflet of maidenhair fern, Fig. 45.
Range: A native of northern China and introduced into eastern North America.
Soil and location: The gingko will grow in poor soils.
Enemies: Practically free from insects and disease.
Value for planting: It makes a valuable tree for the street where heavy shade is not the object and forms an excellent wide-spreading specimen tree on the lawn.
Other characters: The fruit consists of a stone covered by sweet, ill-smelling flesh. The tree is dioecious, there being separate male and female trees. The male tree is preferable for planting in order to avoid the disagreeable odor of the fruit which appears on the female trees when about thirty years old. The male tree has a narrower crown than the female tree. The buds (Fig. 46) are very odd and are conspicuous on the tree throughout the winter. The leaves of the gingko shed in the winter. In this respect the tree is like the larch and the bald cypress.
The gingko belongs to the yew family, which is akin to the pine family. It is therefore a very old tree, the remains of the forests of the ancient world. The gingko in its early life is tall and slender with its few branches close to the stem. But after a time the branches loosen up and form a wide-spreading crown. In the Orient it attains enormous proportions and in this country it also grows to a fairly large size when planted on the open lawn or in groups far apart from other trees so that it can have plenty of room to spread. It then produces a picturesque effect of unusual interest.
WEEPING WILLOW (Salix babylonica)
Distinguishing characters: All the willows have a single cap-like scale to the bud, and this species has an unusually *drooping mass of slender branchlets* which characterizes the tree from all others, Fig. 47.
Form and size: It grows to large size.
Range: Asia and Europe and naturalized in eastern United States.
Soil and location: Prefers moist places near streams and ponds.
Enemies: None of importance.
Value for planting: The weeping willow has a special ornamental effect in cemeteries and along lakes and river banks in parks.
Commercial value: It is used in the United States for charcoal and for fuel.
Comparisons: The pussy willow (Salix discolor) may easily be told from the other willows by its small size; it is often no higher than a tall shrub. Its branches are reddish green and the buds are dark red, smooth and glossy. The predominating color of the twigs and buds in the pussy willow is therefore a shade of red, while in the weeping willow it is yellowish green.
GROUP VII. TREES TOLD BY THEIR BARK OR TRUNK: SYCAMORE, BIRCH, BEECH, BLUE BEECH, IRONWOOD, AND HACKBERRY
How to tell them from other trees: The color of the bark or the form of the trunk of each of the trees in this group is distinct from that of any other tree.
How to tell them from each other: In the sycamore, the bark is mottled; in the white birch, it is dull white; in the beech, it is smooth and gray; in the hackberry, it is covered with numerous corky warts; in the blue beech, the trunk of the tree is fluted, as in Fig. 54, and in the ironwood, the bark peels in thin perpendicular strips.
THE SYCAMORE OR PLANE TREE (Platanus occidentalis)
Distinguishing characters: The peculiar *mottled appearance* of the *bark* (Fig. 48) in the trunk and large branches is the striking character here. The bark produces this effect by shedding in large, thin, brittle plates. The newly exposed bark is of a yellowish green color which often turns nearly white later on. *Round seed balls*, about an inch in diameter, may be seen hanging on the tree all winter. In this species, the seed balls are usually solitary, while in the Oriental sycamore, a European tree similar to the native one, they appear in clusters of two, or occasionally of three or four. See Fig. 49.
Leaf: The stem of the leaf completely covers the bud. This is a characteristic peculiar to sycamores.
Form and size: A large tree with massive trunk and branches and a broad head.
Range: Eastern and southern United States.
Soil and location: Prefers a deep rich soil, but will adapt itself even to the poor soil of the city street.
Enemies: The sycamore is frequently attacked by a fungus (Gloeosporium nervisequum), which curls up the young leaves and kills the tips of the branches. Late frosts also often injure its young twigs. The Oriental sycamore, which is the European species, is more hardy in these respects than the native one and is therefore often chosen as a substitute.
Value for planting: The Occidental sycamore is now planted very little, but the Oriental sycamore is used quite extensively in its place, especially as a shade tree. The Oriental sycamore is superior to the native species in many ways. It is more shapely, faster growing, and hardier than the native one. Both sycamores will bear transplanting and pruning well.
Commercial value: The wood of the sycamore is coarse-grained and hard to work; used occasionally for inside finishing in buildings.
Other names: Buttonball, buttonwood.
Comparisons: The Oriental sycamore (Platanus orientalis) an introduced species, is apt to be confused with the Occidental sycamore, but may be told from the latter by the number of seed balls suspended from the tree. In the case of the Oriental species, the seed balls hang in pairs or (rarely) three or four together. In the Occidental, the seed balls are generally solitary and very rarely in pairs.
GRAY OR WHITE BIRCH (Betula populifolia)
Distinguishing characters: The *dull-white color of the bark* on the trunk and the dark triangular patches below the insertion of the branches distinguish this tree; see Fig. 50. The bark of the young trunks and branches is reddish-brown in color and glossy. The bark adheres closely to the trunk of the tree and does not peel in loose, shaggy strips, as in the case of the yellow or golden birch. It is marked by small raised horizontal lines which are the lenticels or breathing pores. These lenticels are characteristic of all birch and cherry trees. In addition to the distinction in the color of the bark, an important character which distinguishes the gray birch from all other species of birch, is found in the *terminal twigs*, which are *rough* to the touch.
Form and size: A small tree. Frequently grows in clumps.
Range: Eastern United States.
Soil and location: The gray birch does best in a deep, rich soil, but will also grow in poor soils.
Enemies: The bronze-birch borer, a wood-destroying insect, and Polyporus betulinus, a fungus, are its chief enemies.
Value for planting: Its graceful habit and attractive bark gives the tree an important place in ornamental planting. It may be used to advantage with evergreens, and produces a charming effect when planted by itself in clumps.
Commercial value: The wood is soft and not durable. It is used in the manufacture of small articles and for wood pulp.
Other characters: The fruit is a catkin.
Comparisons: The paper birch (Betula papyrifera) is apt to be confused with the gray birch, because both have a white bark. The bark of the paper birch, however, is a clear white and peels off in thin papery layers instead of being close. It very seldom shows any dark triangular markings on the trunk. Its terminal twigs are not rough and its trunk is usually straighter and freer from branches.
The black or sweet birch (Betula lenta) has a bark similar to the gray birch, except that its color is dark gray. See Fig. 51. The twigs have an aromatic taste.
The yellow birch (Betula lutea) has a yellowish or golden bark which constantly peels in thin, ragged, horizontal films.
The European white birch (Betula alba) has a dull-white bark like the native white birch, but has smooth terminal twigs instead of rough ones. It is commonly seen in the United States on lawns and in parks.
AMERICAN BEECH (Fagus americana)
Distinguishing characters: The *close-fitting, smooth, gray bark* will tell this tree from all others except the red maple and yellow-wood. See Fig. 52. The red maple may then be easily eliminated by noting whether the branches are alternate or opposite. They are alternate in the beech and opposite in the maple. The yellow-wood may be eliminated by noting the size of the bud. The *bud* in the yellow-wood is hardly noticeable and of a golden yellow color, while that of the beech is very *long, slender, and sharp-pointed*, and chestnut brown in color. See Fig. 53.
Form and size: It grows tall in the woods, but on the open lawn spreads out into a massive, round-headed tree.
Range: Eastern Canada and United States.
Soil and location: Prefers a rich, well-drained soil, but will grow in any good soil.
Enemies: Aphides or plant lice that suck the sap from the leaves in spring and early summer are the chief enemies of the tree.
Value for planting: The pleasing color of its bark, its fine spread of branches, which gracefully droop down to the ground, and its autumnal coloring, make the beech a favorite for lawn and park planting. The several European species of beech are equally charming.
Commercial value: The wood is strong, close-grained, and tough. It is used mainly for cooperage, tool handles, shoe lasts, chairs, etc., and for fuel.
Other characters: The fruit is a prickly burr encasing a sharply triangular nut which is sweet and edible.
Comparisons: The European beech (Fagus sylvatica), and its weeping, purple-leaved, and fern-leaved varieties, are frequently met with in parks and may be told from the native species by its darker bark. The weeping form may, of course, be told readily by its drooping branches. The leaves of the European beeches are broader and less serrated than those of the American beech.
BLUE BEECH OR HORNBEAM (Carpinus caroliniana)
Distinguishing characters: The *fluted* or muscular effect of its *trunk* will distinguish the tree at a glance, Fig. 54.
Leaf: Doubly serrated; otherwise the same as that of ironwood.
Form and size: A low-spreading tree with branches arching out at various angles, forming a flattened head with a fine, slender spray.
Range: Very common in the eastern United States.
Soil and location: Grows in low wet woods.
Enemies: None of importance.
Value for planting: Its artistic branching and curious trunk give the tree an important place in park planting.
Commercial value: None.
Other characters: The bark is smooth and bluish gray in color.
Comparisons: The blue beech or hornbeam is often confused with the ironwood or hop hornbeam (Ostrya virginiana). The ironwood, however, has a characteristic bark that peels in perpendicular, short, thin segments, often loose at the ends. See Fig. 55. This is entirely different from the close, smooth, and fluted bark of the blue beech. The color of the bark in the ironwood is brownish, while that of the blue beech is bluish-gray. The buds of the ironwood are greenish with brown tips, while the bud of the blue beech shows no green whatever.
HACKBERRY (Celtis occidentalis)
Distinguishing characters: The tree may be told readily from other trees by the *corky tubercles* on the bark of the lower portion of the trunk. See Fig. 56.
Leaf: Has three predominating veins and is a bit more developed on one side than on the other.
Form and size: A small or medium-sized tree with a single stem and broad conical crown.
Range: United States and Canada.
Soil and location: Grows naturally in fertile soils, but will adapt itself to almost sterile soils as well.
Enemies: The hackberry is usually free from disease, though often its leaves are covered with insect galls.
Value for planting: It is extensively planted as a shade tree in the Middle West, and is frequently seen as an ornamental tree in the East.
Commercial value: It has little economic value except for fuel.
Other characters: The fruit is berry-like, with a hard pit. The fleshy outer part is sweet.
Other common names: Nettle tree; sugarberry.
GROUP VIII. THE OAKS AND CHESTNUT
How to tell them from other trees: The oaks are rather difficult to identify and, in studying them it will often be necessary to look for more than one distinguishing character. The oaks differ from other trees in bearing acorns. Their leaves have many lobes and their upper lateral buds cluster at the top of the twigs. The general contour of each oak presents a characteristic branching and sturdiness uncommon in other trees.
The chestnut differs from other trees in bearing burs and its bark is also distinctly characteristic.
How to tell them from each other: There are two groups of oaks, the white oak and the black oak. The white oaks mature their acorns in one year and, therefore, only acorns of the same year can be found on trees of this group. The black oaks take two years in which to mature their acorns and, therefore, young acorns of the present year and mature acorns of the previous year may be found on the same tree at one time. The leaves of the white oaks have rounded margins and rounded lobes as in Fig. 57, while those of the black oaks have pointed margins and sharp pointed lobes as shown in Figs. 60, 62 and 64. The bark of the white oaks is light colored and breaks up in loose flakes as in Fig. 58, while that of the black oaks is darker and deeply ridged or tight as in Figs. 59 and 61. The white oak is the type of the white oak group and the black, red and pin oaks are types of the other. For the characterization of the individual species, the reader is referred to the following pages.
WHITE OAK (Quercus alba)
Distinguishing characters: The massive ramification of its branches is characteristic of this species and often an easy clue to its identification. The *bark* has a *light gray color*—lighter than that of the other oaks—and breaks into soft, loose flakes as in Fig. 58. The *leaves are deeply lobed* as in Fig. 57. The *buds are small, round and congested* at the end of the year's growth. The acorns usually have no stalks and are set in shallow, rough cups. The kernels of the acorns are white and palatable.
Form and size: The white oak grows into a large tree with a wide-spreading, massive crown, dissolving into long, heavy, twisted branches. When grown in the open it possesses a short sturdy trunk; in the forest its trunk is tall and stout.
Range: Eastern North America.
Soil and location: The white oak thrives in almost any well-drained, good, deep soil except in a very cold and wet soil. It requires plenty of light and attains great age.
Enemies: The tree is comparatively free from insects and disease except in districts where the Gipsy moth is common, in which case the leaves of the white oak are a favorite food of its caterpillars.
Value for planting: The white oak is one of the most stately trees. Its massive form and its longevity make the tree suitable for both lawn and woodland planting but it is not used much because it is difficult to transplant and grows rather slowly.
Commercial value: The wood is of great economic importance. It is heavy, hard, strong and durable and is used in cooperage, construction work, interior finish of buildings and for railroad ties, furniture, agricultural implements and fuel.
Comparisons: The swamp white oak (Quercus platanoides) is similar to the white oak in general appearance of the bark and form and is therefore liable to be confused with it. It differs from the white oak, however, in possessing a more straggly habit and in the fact that the bark on the under side of its branches shags in loose, large scales. Its buds are smaller, lighter colored and more downy and its acorns are more pointed and with cups more shallow than those of the white oak. The tree also grows in moister ground, generally bordering swamps.
BLACK OAK (Quercus velutina)
Distinguishing characters: The *bark* is black, rough and cut up into firm *ridges* especially at the base of the tree, see Fig. 59. The inner bark has a bright yellow color: the *leaves* have sharp points and are wider at the base than at the tip as shown in Fig. 60. The buds are large, downy and sharp pointed. The acorns are small and have deep, scaly cups the inner margins of which are downy. The kernels are yellow and bitter.
Form and size: The tree grows in an irregular form to large size, with its branches rather slender as compared with the white oak and with a more open and narrow crown.
Range: Eastern North America.
Soil and location: It will grow in poor soils but does best where the soil is rich and well drained.
Enemies: None of importance.
Value for planting: The black oak is the poorest of the oaks for planting and is rarely offered by nurserymen.
Commercial value: The wood is heavy, hard and strong, but checks readily and is coarse grained. It is of little value except for fuel. The bark is used for tannin.
Other common names: Yellow oak.
Comparisons: The black oak might sometimes be confused with the red and scarlet oaks. The yellow, bitter inner bark will distinguish the black oak from the other two. The light-colored, smooth bark of the red oak and the dark, ridged bark of the black oak will distinguish the two, while the bark of the scarlet oak has an appearance intermediate between the two. The buds of the three species also show marked differences. The buds of the black oak are covered with hairs, those of the scarlet oak have fewer hairs and those of the red are practically free from hairs. The leaves of each of the three species are distinct and the growth habits are different.
RED OAK (Quercus rubra)
Distinguishing characters: The *bark* is perpendicularly fissured into long, smooth, light gray strips giving the trunk a characteristic *pillar effect* as in Figs. 61 and 94. It has the straightest trunk of all the oaks. The leaves possess more lobes than the leaves of any of the other species of the black oak group, see Fig. 62. The acorns, the largest among the oaks, are semispherical with the cups extremely shallow. The buds are large and sharp pointed, but not as large as those of the black oak. They also have a few fine hairs on their scales, but are not nearly as downy as those of the Black oak.
Form and size: The red oak is the largest of the oaks and among the largest of the trees in the northern forests. It has a straight trunk, free from branches to a higher point than in the white oak, see Fig. 94. The branches are less twisted and emerge at sharper angles than do those of the white oak.
Range: It grows all over Eastern North America and reaches north farther than any of the other oaks.
Soil and location: It is less fastidious in its soil and moisture requirements than the other oaks and therefore grows in a great variety of soils. It requires plenty of light.
Enemies: Like most of the other oaks, this species is comparatively free from insects and disease.
Value for planting: The red oak grows faster and adapts itself better to poor soil conditions than any of the other oaks and is therefore easy to plant and easy to find in the nurseries. It makes an excellent street tree, is equally desirable for the lawn and is hardly surpassed for woodland planting.
Commercial value: The wood is hard and strong but coarse grained, and is used for construction timber, interior finish and furniture. It is inferior to white oak where strength and durability are required.
PIN OAK (Quercus palustris)
Distinguishing characters: Its method of *branching* will characterize the tree at a glance. It develops a well-defined main ascending stem with numerous drooping side branches as in Fig. 63. The buds are very small and sharp pointed and the leaves are small as in Fig. 64. The bark is dark, firm, smooth and in close ridges. The acorn is small and carries a light brown, striped nut, wider than long and bitter. The cup is shallow, enclosing only the base of the nut.
Form and size: The pin oak is a medium-sized tree in comparison with other oaks. It develops a tall, straight trunk that tapers continuously through a pyramidal crown of low, drooping tender, branches.
Range: Eastern North America.
Soil and location: It requires a deep, rich, moist soil and grows naturally near swamps. Its roots are deep and spreading. The tree grows rapidly and is easily transplanted.
Enemies: None of importance.
Value for planting: The pin oak is an extremely graceful tree and is therefore extensively used for planting on lawns and on certain streets where the tree can find plenty of water and where conditions will permit its branches to droop low.
Commercial value: The wood is heavy and hard but coarse grained and liable to check and warp. Its principal use is in the construction of houses and for shingles.
CHESTNUT (Castanea dentata)
Distinguishing characters: The *bark* in young trees is smooth and of a marked reddish-bronze color, but when the tree grows older, the bark breaks up into *diamond-shaped ridges*, sufficiently characteristic to distinguish the tree at a glance, see Fig. 65. A close examination of the terminal twig will show three ridges and two grooves running down along the stem from the base of each leaf or leaf-scar. The twig has no true terminal bud. The fruit, a large, round *bur*, prickly without and hairy within and enclosing the familiar dark brown, sweet edible nuts is also a distinguishing mark of the tree.
Leaf: The leaves are distinctly long and narrow. They are from 6 to 8 inches long.
Form and size: The chestnut is a large tree with a massive trunk and broad spreading crown. The chestnut tree when cut, sprouts readily from the stump and therefore in places where the trees have once been cut, a group of two to six trees may be seen emerging from the old stump.
Range: Eastern United States.
Soil and location: It will grow on rocky as well as on fertile soils and requires plenty of light.
Enemies: During the past nine years nearly all the chestnut trees in the United States have been attacked by a fungus disease (Diaporthe parasitica, Mur.) which still threatens the entire extinction of the chestnut trees in this country. No remedy has been discovered and all affected trees should be cut down and the wood utilized before it decays and becomes worthless. No species of chestnut tree is entirely immune from this disease, though some species are highly resistant.
Value for planting: The chestnut is one of the most rapidly growing hardwood trees but, on account of its disease, which is now prevalent everywhere, it is not wise to plant chestnut trees for the present.
Commercial value: The wood is light, not very strong and liable to warp. It is durable when brought in contact with the soil and is therefore used for railroad ties, fence-posts, poles, and mine timbers. It is also valuable for interior finish in houses and for fuel. Its bark is used in the manufacture of tanning extracts and the nuts are sold in cities in large quantities.
HOW TO IDENTIFY TREES—(Continued)
GROUP IX. THE HICKORIES, WALNUT AND BUTTERNUT
How to tell them from other trees and from each other: The hickory trees, though symmetrical, have a rugged appearance and the branches are so sturdy and black as to give a special distinction to this group. The buds are different from the buds of all other trees and sufficiently characteristic to distinguish the various species of the group. The bark is also a distinguishing character.
The walnut and butternut have chambered piths which distinguish them from all other trees and from each other.
SHAGBARK HICKORY (Hicoria ovata)
Distinguishing characters: The yellowish brown *buds* nearly as large as those of the mockernut hickory, are each provided with two long, dark, outer scales which stand out very conspicuously as shown in Fig. 67. The *bark* in older specimens *shags* off in rough strips, sometimes more than a foot long, as shown in Fig. 68. These two characters will readily distinguish the tree at all seasons of the year.
Leaf: The leaf is compound, consisting of 5 or 7 leaflets, the terminal one generally larger.
Form and size: A tall, stately tree—the tallest of the hickories—of rugged form and fine symmetry, see Fig. 66.
Range: Eastern North America.
Soil and location: The shagbark hickory grows in a great variety of soils, but prefers a deep and rather moist soil.
Enemies: The hickory bark borer (Scolytus quadrispinosus) is its principal enemy. The insect is now killing thousands of hickory trees in the vicinity of New York City and on several occasions has made its appearance in large numbers in other parts of the country.
Value for planting: It is difficult to transplant, grows slowly and is seldom found in nurseries.
Commercial value: The wood is extremely tough and hard and is used for agricultural implements and for the manufacture of wagons. It is excellent for fuel and the nuts are of great value as a food.
Other characters: The fruit is a nut covered by a thick husk that separates into 4 or 5 segments. The kernel is sweet.
Other common names: Shellbark hickory.
MOCKERNUT HICKORY (Hicoria alba)
Distinguishing characters: The *bud* is the largest among the hickories—nearly half an inch long—is hard and oval and covered with yellowish brown downy scales which do not project like those of the shagbark hickory, see Fig. 69. The twigs are extremely coarse. The *bark* is very tight on the trunk and branches and has a close, hard, wavy appearance as in Fig. 70.
Leaf: The leaf consists of 5, 7 or 9 leaflets all of which are large and pubescent and possess a distinct resinous odor.
Form and size: A tall tree with a broad spreading head.
Range: Eastern North America.
Soil and location: The mockernut hickory grows on a great variety of soils, but prefers one which is rich and well-drained.
Enemies: The same as for the shagbark hickory.
Value for planting: It is not commonly planted.
Commercial value: The wood is similar to that of the shagbark hickory and is put to the same uses.
Other characters: The fruit is a nut, larger and covered with a shell thicker than that of the shagbark. The husk is also thicker and separates into four segments nearly to the base. The kernel is small and sweet.
Other common names: Bigbud hickory; whiteheart hickory.
Comparisons: The pignut hickory (Hicoria glabra), sometimes called broom hickory or brown hickory, often has a shaggy bark, but differs from both the shagbark and the mockernut hickory in possessing buds very much smaller, twigs more slender and leaflets fewer. The nut has a thinner husk which does not separate into four or five segments. The tree prefers drier ground than the other hickories.
The bitternut (Hicoria minima) can be told from the mockernut and other species of hickory by its bud, which has no scales at all. The color of its bud is a characteristic orange yellow. The bark is of a lighter shade than the bark of the mockernut hickory and the leaflets are more numerous than in any of the hickories, varying from 7 to 11. Its nuts are bitter.
BLACK WALNUT (Juglans nigra)
Distinguishing characters: By cutting a twig lengthwise, it will be seen that its *pith* is divided into little chambers as shown in Fig. 71. The bud is dark gray and satiny. The bark is dark brown and deeply ridged and the fruit is the familiar round walnut.
Form and size: A tall tree with a spreading crown composed of stout branches. In the open it grows very symmetrically.
Range: Eastern United States.
Soil and location: The black walnut prefers a deep, rich, fertile soil and requires a great deal of light.
Enemies: The tree is a favorite of many caterpillars.
Value for planting: It forms a beautiful spreading tree on open ground, but is not planted to any extent because it is hard to transplant. It grows slowly unless the soil is very deep and rich, develops its leaves late in the spring and sheds them early in the fall and produces its fruit in great profusion.
Commercial value: The wood is heavy, strong, of chocolate brown color and capable of taking a fine polish. It is used for cabinet making and interior finish of houses. The older the tree, usually, the better the wood, and the consumption of the species in the past has been so heavy that it is becoming rare. The European varieties which are frequently planted in America as substitutes for the native species yield better nuts, but the American species produces better wood.
Other characters: The fruit is a large round nut about two inches in diameter, covered with a smooth husk which at first is dull green in color and later turns brown. The husk does not separate into sections. The kernel is edible and produces an oil of commercial value.
The leaves are compound and alternate with 15 to 23 leaflets to each.
Comparisons: The butternut (Juglans cinerea) is another tree that has the pith divided into little chambers, but the little chambers here are shorter than in the black walnut, as may be seen from a comparison of Figs. 71 and 72. The bark of the butternut is light gray while that of the black walnut is dark. The buds in the butternut are longer than those of the black walnut and are light brown instead of gray in color. The form of the tree is low and spreading as compared with the black walnut. The fruit in the butternut is elongated while that of the black walnut is round. The leaves of the butternut have fewer leaflets and these are lighter in color.
GROUP X. TULIP TREE, SWEET GUM, LINDEN, MAGNOLIA, LOCUST, CATALPA, DOGWOOD, MULBERRY AND OSAGE ORANGE
TULIP TREE (Liriodendron tulipifera)
Distinguishing characters: There are four characters that stand out conspicuously in the tulip tree—the *bud*, the *trunk*, the persistent *fruit cups* and the wedged *leaf*.
The bud, Fig. 74, about three-quarters of an inch long, is covered by two purplish scales which lend special significance to its whole appearance. The trunk is extremely individual because it rises stout and shaft-like, away above the ground without a branch as shown in Fig. 73. The tree flowers in the latter part of May but the cup that holds the fruit persists throughout the winter. The leaf, Fig. 75, has four lobes, is nearly as broad as it is long and so notched at the upper end that it looks different from any other leaf.
Form and size: The tulip tree is one of the largest, stateliest and tallest of our trees.
Range: Eastern United States.
Soil and location: Requires a deep, moist soil.
Enemies: Comparatively free from insects and disease.
Value for planting: The tree has great value as a specimen on the lawn but is undesirable as a street tree because it requires considerable moisture and transplants with difficulty. It should be planted while young and where it can obtain plenty of light. It grows rapidly.
Commercial value: The wood is commercially known as whitewood and yellow poplar. It is light, soft, not strong and easily worked. It is used in construction, for interior finish of houses, woodenware and shingles. It has a medicinal value.
Other characters: The flower, shown in Fig. 75, is greenish yellow in color, appears in May and resembles a tulip; hence the name tulip tree. The fruit is a cone.
Other common names: Whitewood; yellow poplar; poplar and tulip poplar.
SWEET GUM (Liquidambar styraciflua)
Distinguishing characters: The persistent, spiny, long-stemmed round *fruit*; the corky growths on the *twigs*, the characteristic star-shaped *leaves* (Fig. 76) and the very shiny greenish brown buds and the perfect symmetry of the tree are the chief characters by which to identify the species.
Form and size: The sweet gum has a beautiful symmetrical shape, forming a true monopodium.
Range: From Connecticut to Florida and west to Missouri.
Soil and location: Grows in any good soil but prefers low wet ground. It grows rapidly and needs plenty of light.
Enemies: Is very often a favorite of leaf-eating caterpillars.
Value for planting: The tree is sought for the brilliant color of its foliage in the fall, and is suitable for planting both on the lawn and street. In growing the tree for ornamental purposes it is important that it should be frequently transplanted in the nursery and that it be transported with burlap wrapping around its roots.
Commercial value: The wood is reddish brown in color, tends to splinter and is inclined to warp in drying. It is used in cooperage, veneer work and for interior finish.
Other characters: On the smaller branches there are irregular developments of cork as shown in Fig. 76, projecting in some cases to half an inch in thickness.
Other common names: Red gum.
Comparisons: The cork elm is another tree that possesses corky ridges along its twigs, but this differs from the sweet gum in wanting the spiny fruit and its other distinctive traits.
AMERICAN LINDEN (Tilia Americana)
Distinguishing characters: The great distinguishing feature of any linden is the *one-sided* character of its *bud* and *leaf*. The bud, dark red and conical, carries a sort of protuberance which makes it extremely one sided as shown in Fig. 77. The leaf, Fig. 78, is heart-shaped with the side nearest the branch largest.
Form and size: The American Linden is a medium-sized tree with a broad round head.
Range: Eastern North America and more common in the north than in the south.
Soil and location: Requires a rich, moist soil.
Enemies: Its leaves are a favorite food of caterpillars and its wood is frequently attacked by a boring insect known as the linden borer (Saperda vestita).
Value for planting: The linden is easily transplanted and grows rapidly. It is used for lawn and street planting but is less desirable for these purposes than the European species.
Commercial value: The wood is light and soft and used for paper pulp, woodenware, cooperage and furniture. The tree is a favorite with bee keepers on account of the large quantities of nectar contained in its flowers.
Other characters: The fruit is like a pea, gray and woody. The flowers appear in early July, are greenish-yellow and very fragrant.
Other common names: Bass-wood; lime-tree; whitewood.
Comparisons: The European lindens, Fig. 79, of which there are several species under cultivation, differ from the native species in having buds and leaves smaller in size, more numerous and darker in color.
The various species of magnolia trees are readily distinguished by their buds. They all prefer moist, rich soil and have their principal value as decorative trees on the lawn. They are distinctly southern trees; some species under cultivation in the United States come from Asia, but the two most commonly grown in the Eastern States are the cucumber tree and the umbrella tree.
CUCUMBER TREE (Magnolia acuminata)
Distinguishing characters: The *buds* are small and slender compared with those of the other magnolia trees and are covered with small silvery silky hairs. The *habit* of the tree is to form a straight axis of great height with a symmetrical mass of branches, producing a perfect monopodial crown. The tree is sometimes known as mountain magnolia.
UMBRELLA TREE (Magnolia tripetala)
Distinguishing characters: The buds, Fig. 80, are extremely long, often one and a half inches, have a purple color and are smooth. The tree does not grow to large size and produces an open spreading head. Its leaves, twelve to eighteen inches long, are larger than those of the other magnolia trees. The tree is sometimes called elkwood.
BLACK LOCUST (Robinia pseudacacia)
Distinguishing characters: The *bark* of the trunk is rough and deeply ridged, as shown in Fig. 81. The *buds* are hardly noticeable; the twigs sometimes bear small spines on one side. The leaves are large, compound, and fern-like. The individual leaflets are small and delicate.
Form and size: The locust is a medium-sized tree developing a slender straight trunk when grown alongside of others; see Fig. 82.
Range: Canada and United States.
Soil and location: The locust will grow on almost any soil except a wet, heavy one. It requires plenty of light.
Enemies: The locust borer has done serious damage to this tree. The grubs of this insect burrow in the sapwood and kill the tree or make it unfit for commercial use. The locust miner is a beetle which is now annually defoliating trees of this species in large numbers.
Value for planting: It has little value for ornamental planting.
Commercial value: Though short-lived, the locust grows very rapidly. It is extremely durable in contact with the soil and possesses great strength. It is therefore extensively grown for fence-posts and railroad ties. Locust posts will last from fifteen to twenty years. The wood is valuable for fuel.
Other characters: The flowers are showy pea-shaped panicles appearing in May and June. The fruit is a small pod.
Other common names: Yellow locust; common locust; locust.
Comparisons: The honey locust (Gleditsia triacanthos) can be told from the black locust by the differences in their bark. In the honey locust the bark is not ridged, has a sort of dark iron-gray color and is often covered with clusters of stout, sharp-pointed thorns as in Fig. 83. The fruit is a large pod often remaining on the tree through the winter. This tree has an ornamental, but no commercial value.
HARDY CATALPA (Catalpa speciosa)
Distinguishing characters: The tree may be told by its *fruit*, which hang in long slender pods all winter. The leaf-scars appear on the stem in whorls of three and rarely opposite each other.
Form and size: The catalpa has a short, thick and twisted trunk with an irregular head.
Range: Central and eastern United States.
Soil and location: It grows naturally on low bottom-lands but will also do well in poor, dry soils.
Enemies: Practically free from disease and insects.
Value for planting: The catalpa grows very rapidly and is cultivated in parks for ornament and in groves for commercial purposes. The hardy catalpa is preferable to the common catalpa for planting.
Commercial value: The wood is extremely durable in contact with the soil and is consequently used for posts and railroad ties.
Other characters: The flowers, which appear in late June and early July, are large, white and very showy.
Other common names: Indian bean; western catalpa.
Comparisons: The white flowering dogwood (Cornus florida) is a small tree which also has its leaves in whorls of three or sometimes opposite. It can be readily told from other trees, however, by the small square plates into which the outer bark on the trunk divides itself, see Fig. 85, and by the characteristic drooping character of its branches. It is one of the most common plants in our eastern deciduous forests. It is extremely beautiful both in the spring and in the fall and is frequently planted for ornament. There are many varieties of dogwood in common use.
WHITE MULBERRY (Morus alba)
A small tree recognized by its small round reddish brown buds and light brown, finely furrowed (wavy looking) bark.
The tree, probably a native of China, is grown under cultivation in eastern Canada and United States. It grows rapidly in moist soil and is not fastidious in its light requirements. Its chief value is for screening and for underplanting in woodlands.
The red mulberry (Morus rubra) is apt to be confused with the white mulberry, but differs in the following characters: The leaves of the red mulberry are rough on the upper side and downy on the under side, whereas the leaves of the white mulberry are smooth and shiny. The buds in the red are larger and more shiny than those of the white.
The Osage orange (Toxylon pomiferum) is similar to the mulberry in the light, golden color of its bark, but differs from it in possessing conspicuous spines along the twigs and branches and a more ridged bark.
THE STRUCTURE AND REQUIREMENTS OF TREES
To be able fully to appreciate trees, their mode of life, their enemies and their care, one must know something of their structure and life requirements.
Structure of trees: Among the lower forms of plants there is very little distinction between the various parts—no differentiation into root, stem, or crown. Often the lower forms of animal and vegetable life are so similar that one cannot discriminate between them. But as we ascend in the scale, the various plant forms become more and more complex until we reach the tree, which is the largest and highest form of all plants. The tree is a living organism composed of cells like any other living organism. It has many parts, every one of which has a definite purpose. The three principal parts are: the stem, the crown, and the root.
The stem: If we examine the cross-section of a tree, Fig. 86, we will notice that it is made up of numerous rings arranged in sections of different color and structure. The central part is known as the pith. Around the pith comes a dark, close-grained series of rings known as the heartwood, and outside the heartwood comes a lighter layer, the sapwood. The cambium layer surrounds the sapwood and the bark covers all. The cambium layer is the most important tissue of the tree and, together with part of the sapwood, transports the water and food of the tree. It is for this reason that a tree may be hollow, without heart and sapwood, and still produce foliage and fruit.
The crown: The crown varies in form in different species and is developed by the growth of new shoots from buds. The bud grows out to a certain length and forms the branch. Afterwards it thickens only and does not increase in length. New branches will then form from other buds on the same branch. This explains in part the characteristic branching of trees, Fig. 87.
The leaves are the stomach and lungs of the tree. Their broad blades are a device to catch the sunlight which is needed in the process of digesting the food of the tree. The leaves are arranged on the twigs in such a way as to catch the most sunlight. The leaves take up the carbonic acid gas from the air, decompose it under the influence of light and combine it with the minerals and water brought up by the roots from the soil. The resulting chemical combinations are the sugars and starches used by the cambium layer in building up the body of the tree. A green pigment, chlorophyll, in the leaf is the medium by which, with the aid of sunlight, the sugars are manufactured.
The chlorophyll gives the leaf its green color, and this explains why a tree pales when it is in a dying condition or when its life processes are interfered with. The other colors of the leaf—the reds, browns and yellows of the fall or spring—are due to other pigments. These are angular crystals of different hues, which at certain times of the year become more conspicuous than at others, a phenomenon which explains the variation in the colors of the leaves during the different seasons.
It is evident that a tree is greatly dependent upon its leaves for the manufacture of food and one can, therefore, readily see why it is important to prevent destruction of the leaves by insects or through over-trimming.
The root: The root develops in much the same manner as the crown. Its depth and spread will vary with the species but will also depend somewhat upon the condition of the soil around it. A deep or a dry soil will tend to develop a deep root, while a shallow or moist soil will produce a shallow root, Fig. 88.
The numerous fine hairs which cover the roots serve the purpose of taking up food and water from the soil, while the heavy roots help to support the tree. The root-hairs are extremely tender, are easily dried out when exposed to the sun and wind, and are apt to become overheated when permitted to remain tightly packed for any length of time. These considerations are of practical importance in the planting of trees and in the application of fertilizers. It is these fine rootlets far away from the trunk of the tree that have to be fed, and all fertilizers must, therefore, be applied at points some distance from the trunk and not close to it, where merely the large, supporting roots are located. In the cultivation of trees the same principle holds true.
Requirements of trees: Trees are dependent upon certain soil and atmospheric conditions which influence their growth and development.
(1) Influence of moisture: The form of the tree and its growth and structure depend greatly upon the supply of moisture. Botanists have taken the moisture factor as the basis of classification and have subdivided trees into those that grow in moist places (hydrophytes), those that grow in medium soils (mesophytes), and those that grow in dry places (xerophytes). Water is taken up by the roots of the tree from the soil. The liquid absorbed by the roots carries in solution the mineral salts—the food of the tree—and no food can be taken up unless it is in solution. Much of the water is used by the tree and an enormous amount is given off in the process of evaporation.