Form and size: The sweet gum has a beautiful symmetrical shape, forming a true monopodium.
[Illustration: FIG. 76.--Leaf and Fruit of the Sweet Gum. Note the corky ridges along the twig.]
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.
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.
[Illustration: FIG. 77.--Bud of the Linden Tree.]
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.
[Illustration: FIG. 78.--Leaves and Flowers of the European Linden.]
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.
[Illustration: FIG. 79.--European Linden Tree.]
[Illustration: FIG. 80.--Bud of the Umbrella Tree.]
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.