Studies of Trees | Page 9

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.
[Illustration: FIG. 35.--Leaf of Norway Maple.]
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.
[Illustration: Figure 36.--Twig of the Box Elder.]
Enemies: Few.
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.
[Illustration: FIG. 37.--American Elm.]
Leaf: The leaves are simple, alternate, and from 2 to 5 inches long.
[Illustration: FIG. 38.--English Elm in Winter.]
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.
[Illustration: FIG. 39.--Lombardy Poplar.]
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.
[Illustration: FIG. 40.--Leaf of Carolina Poplar.]
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