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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.
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.
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.
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.
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.
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.
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.
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 ¾ of an inch long, which generally hangs on the tree all winter.
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.
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.
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 ½ 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 ( Chamæcyparis thyoides ) but the leaves of the latter are sharp-pointed and not flattened or fan-shaped.