Birch (betula), a genus of monoecious trees or shrubs, which have as generic features both sterile and fertile flowers in scaly catkins, three of each under each bract, with no involucre to the broadly winged nutlet which results from a naked ovary. The sterile catkins are long and drooping, formed in summer, remaining naked through the succeeding winter, and expanding their golden flowers in early spring, preceding the leaves. The fertile catkins are oblong or cylindrical, protected by scales through the winter, and developed with the leaves. The outer bark is usually separable in thin horizontal sheets; the twigs and leaves are often spicy and aromatic, and the foliage is mostly thin and light. The birch and the alder (alnus) were classified in the same genus by Linnaeus in his later works, but are now generally regarded as distinct by botanists. - There are 19 recognized species of birch, for the most part lofty-growing and ornamental trees, found native in Asia, Europe, and America, and almost all preferring th3 cold regions of the northern latitudes.

The most widely extended of them is B. alba, or common white birch, a native of Europe, and found in America, near the coast, from Pennsylvania to Maine, which thrives in every kind of difficult and sterile soil, but decays where the ground is rich. It is found, though dwarfed in size, higher on the Alps than any other tree, approaches near to the icy regions of the north, and is almost the only tree which Greenland produces. It has a chalk-white bark, and triangular, very taper-pointed, shining leaves, tremulous as those of an aspen. It serves many purposes of domestic economy. The bark is employed by the Greenlanders, Laplanders, and inhabitants of Kamtchatka in covering their huts and in making baskets and ropes. An infusion of the leaves makes a yellow dye, and is also drunk like tea by the Finns; and the Russians and Swedes prepare from the sap of the trunk a fermented liquor resembling champagne. - The most graceful tree of the genus is the B. pendula, growing both in mountainous situations and bogs, from Lapland to the subalpine parts of Italy and Asia. Its popular name is the weeping birch, and it is distinguished for its suppleness and the graceful bend and falling inclination of its long boughs.

Its picturesque appearance, with its white and brilliant bark and gleaming, odoriferous leaves, makes it a favorite in parks and gardens. - The B. lenta, cherry or black birch, called also the mountain mahogany from the hardness of its wood, has a dark, chestnut-brown bark, and abounds particularly from New England to Ohio, and on the summits of the Alleghany mountains. Its leaves, bark, and wood are aromatic; the wood is rose-colored, fine-grained, and valuable for cabinet work. - The B. papyracea, or paper birch, is that from which the aborigines of America make the canoes with which they navigate lakes and rivers, and hence it is also called the canoe birch. It is a native of Canada and the northern United States, and is superior to all other species for its tough bark, in paper-like layers, which is so durable that the wood of the fallen tree will rot entirely away while the case of bark remains sound and solid. - The B. nigra, the river or red birch, is an alder-like American species, with whitish leaves and reddish-brown bark, found from Massachusetts to the southern states. Barrel hoops are made from its branches, and its tough twigs are the best materials for coarse brooms.

The negroes also make vessels from it to contain their food and drink. - The B. nana, dwarf or Alpine birch, is a native of the Alps and of the mountains of Lapland. The Laplanders burn it on summer nights to drive off a kind of mosquito, and sleep in the fragrant smoke. It has been introduced into this country, and appears as a small shrub on the summit of mountains in Maine and New Hampshire, and in other frigid situations northward.

Leaves and Catkin of White Birch.

Trunk of White Birch.

Weeping Birch.