Black Birch, Sweet Birch.—The tree familiar to boys because of its aromatic bark, which contains salicylic acid used in treating cases of rheumatism. A large forest tree with handsome foliage, a very fine-winged seed and valuable wood. Heavy, hard, fine-grained, and takes a high polish. Used for wheel hubs, and the manufacture of furniture.
Red Birch.—Found in swamps and along rivers, especially in the South. Leaves smaller than black birch and wood much lighter in weight, but close-grained and strong. Used for furniture and wooden ware.
Yellow Birch.—A northern tree, growing a hundred feet high in northern New York and Canada. Leaves similar to black birch, but its bark is very different. The bark of the black birch is very dark, while that of yellow birch is of a silvery, yellowish gray, characteristic birch bark.
Wood heavy, hard, and similar to black birch. Used for the same general purposes.
White Birch, Canoe Birch, or Paper Birch.—Noted for its remarkable bark. White on the young trees, darker on old ones. Comes off in several distinct paper-like layers. Well known to ancient writers and used by them for paper. It contains a resinous oil which accounts for its water-resisting qualities so well known in the Indian birch-bark canoe. The inner bark contains starch and in the extreme north it is sometimes mixed with other foods. The sap may be used for making sugar. Wood is light brown and light weight but hard, strong, and close-grained. Used for shoe-lasts, fuel, and spools.
Gray Birch, Aspen-Leaved Birch.—Sometimes called white birch. The bark is white but patched with black and does not come off in layers as readily nor separate so easily from the wood as white birch.
A smaller tree with foliage that moves as freely in the wind as the aspen.
Leaf form very peculiar; a long thin stem, broad flat base, and long tapering outline, double serrate. A persistent little tree, very hardy and difficult to kill.
Wood is light and soft, close-grained but weak. Used for pulp, fuel, spools, and hoops.
Hop Hornbeam, Ironwood.—A little tree with delicate birch-like foliage and wood of great hardness. The name hop is derived from the fruit cluster bearing the seeds, which resembles the hop. The bark is in remarkable contrast to the foliage, being deeply furrowed and smooth, as if a smooth skin were drawn over powerful muscles.