Birch

Birch (Betula), a genus of Betulaceæ, which contains only the two genera, Birch and Alder (q.v.), and is frequently reckoned as a sub-order of Amentiferae (q.v.). The twenty-five species of birch are all trees or shrubs, natives of northern, temperate, and arctic regions.—The Common Birch (B. alba) has small, long-stalked, somewhat triangular doubly serrated leaves. It is a very beautiful and rapid growing, but unfortunately short-lived forest-tree, of the colder palæarctic region, which in favourable situations attains a height of 50 to 60 feet, with a diameter of 1 to 1½ feet, but diminishes in size towards its arctic or alpine limit, at last becoming a mere bush. It is the last tree to disappear as we proceed northwards or upwards, and hence the most important tree of Northern Russia, &c., where it often forms whole woods. No other tree exists in Greenland; and according to old popular belief, it was the only tree that grew in paradise. The bark is smooth and silvery white, and its outermost layers are thrown off as the tree advances in age. The smaller branches are very slender and flexible, and in a particularly graceful variety called the Weeping Birch (B. A. pendula of some botanists), they are still more slender, elongated, and pendulous. The bark and leaves of the birch are, in some northern countries, used medicinally in cases of fever and eruptions. They are also used for dyeing ployed in smoking hams, herrings, &c. In many countries the sap is not only used as a beverage in a fresh state, but is converted by fermentation into a kind of wine. The White Birch of North America (B. populifolia) very nearly resembles the common birch, and is also extensively used. The Black Birch of the same country, but of more southern range (B. nigra), also sometimes called Red Birch, produces very hard and valuable timber. But the name Black Birch is also given to another species sometimes called the Sweet Cherry Birch (B. lenta), itself a large and valuable timber-tree. Its leaves make an agreeable tea. The Yellow Birch of Nova Scotia, Maine, &c. (B. excelsa) is a large tree with leaves 3½ inches long; its timber is used in shipbuilding. The bark of the Paper Birch (B. papyracea) is capable of division into very thin sheets, which have been used as a substitute for paper. It is used by the Indians and French Canadians for canoes, boxes, buckets, baskets, &c. Large plates of it are curiously stitched together with the fibrous roots of the White Spruce, and coated with the resin of the Balm of Gilead Fir. B. occidentalis is an interesting species found on the Pacific slope. The mountainous districts of India also produce several useful species. Thin, delicate plates of the bark of B. bhajputra are used for lining the tubes of hookahs, and were formerly used as paper. B. acuminata, a native of Nepal, has strong and durable wood.—The Dwarf Birch (B. nana) is a mere bushy shrub, seldom more than 2 or 3 feet high, and generally much less. It has orbicular crenate leaves. It is a native of the whole of the most northern regions of the globe, and is found as far south as the Highlands of Scotland. It is interesting because of its uses to the Laplanders and other inhabitants of very northern regions, to whom it supplies their chief fuel, and the material with which they stuff their beds. Its seeds are the food of the ptarmigan, on which the Laplanders in a considerable degree depend. A similar shrubby species (B. antarctica) occurs in Tierra del Fuego.