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 _p.u.s.s.y 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 p.u.s.s.y 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.
[Ill.u.s.tration: FIG. 48.--Bark of the Sycamore Tree.]
THE SYCAMORE OR PLANE TREE (_Plata.n.u.s 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 b.a.l.l.s*, about an inch in diameter, may be seen hanging on the tree all winter. In this species, the seed b.a.l.l.s are usually solitary, while in the Oriental sycamore, a European tree similar to the native one, they appear in cl.u.s.ters of two, or occasionally of three or four.
See Fig. 49.
[Ill.u.s.tration: FIG. 49.--Seed-b.a.l.l.s of the Oriental Sycamore. Note one Seed-ball cut in half.]
[Ill.u.s.tration: FIG. 50.--Gray or White Birch Trees.]
Leaf: The stem of the leaf completely covers the bud. This is a characteristic peculiar to sycamores.
Form and size: A large tree with ma.s.sive 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 subst.i.tute.
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.
[Ill.u.s.tration: FIG. 51.--Bark of the Black or Sweet Birch.]
Commercial value: The wood of the sycamore is coa.r.s.e-grained and hard to work; used occasionally for inside finishing in buildings.
Other names: _b.u.t.tonball_, _b.u.t.tonwood_.
Comparisons: The _Oriental sycamore_ (_Plata.n.u.s 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 b.a.l.l.s suspended from the tree. In the case of the Oriental species, the seed b.a.l.l.s hang in _pairs_ or (rarely) three or four together.
In the Occidental, the seed b.a.l.l.s 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, s.h.a.ggy 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.
[Ill.u.s.tration: FIG. 52.--Bark of the Beech.]
[Ill.u.s.tration: FIG. 53.--Buds of the Beech Tree.]
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.
[Ill.u.s.tration: FIG. 54.--Trunk of Blue Beech.]
[Ill.u.s.tration: FIG. 55.--Bark of the Ironwood.]
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 (_f.a.gus 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 ma.s.sive, 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.