BIRCH (betula), a genus of plants of the natural order amentame (q.v.), sub-order betutinea, the natural order betulacete of some botanists. In this order or sub-order which contains only the two genera, birch and alder (q.v )—the flowers have merely small scales for their perianth; the ovary is two-celled, but the fruit—a small stelienium (q.v.)—is by abortion one-celled; the fruits and scales united form a sort of cone: and the leaves have stipules which soon fall off. They are all trees or shrubs, natives of temperate and cold regions.—The genus Letitia is distinguished by 10 to 12 stamens, and winged achenia.—The common B. (betiekt albs) has small ovato-triangular doubly serrated leaves. It is a very beautiful forest-tree, abounding in the n. of Europe and of Asia, often forming large groves by itself. In the s. of Europe, it is found only upon mountains of considerable elevation. It is a tree of rapid growth. In favorable situa tions, it attains the height of 60 or even 70 ft.. with a diameter of 1-.1 or 2 ft.; whilst ou the northern, or utmost alpine limits of vegetation, it only appears as a stunted bush. 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 B. (B. pendula of some botanists), they arc still more slender, elongated, and pendulous. Some of the finest weeping birches in Britain stand on the banks of the river Findhorn, near Forres, in Morayshire; they are 60 ft. high, and exhibit pendent masses of spray 10 ft. in length. The bark and leaves of the B. are, in some northern countries, used medicinally in cases of fever and eruptions, They are also used for dyeing yellow. The bark is sometimes used for tanning, and is preferred to every other kind of bark for steeping nets, sails, and cordage. See BARR FOR Taxsorso. It is in some countries made into shoes, hats, drinking-cups, etc., and it is even twisted into a coarse kind of ropes. Portable boats made of it are used on the Volga. It is remarkable for durability. In many parts of the n. of Europe, it is used instead of slates or shingles by the peasantry; and in Russia—the outer or white layers being subjected to distillation—there is obtained a reddish empyreumatic oil called B. oil; It yields also the 13. tar, or degutt, which is employed in the preparation of Russia leather. Dried, ground, and mixed with meal, B. bark is used in Norway for feeding swine; and, in times of scarcity, has even served for human food. The wood is in universal use in northern countries for the most various purposes. It is white, firm. and tough, and is employed by wheelwrights, coopers, turners, etc. It is very much employed in the numnfrietare of barrels for fish. It iR much employed for smoking hams, herrings, etc., becau-c of the flavor which it imparts. Much of it is made into charcoal for forges. The twigs are in general use for besoms. In the highlands of Scotland, and in many other countries, the sap is not only used as a beverage in a fresh state, but is converted by fermentation into a kind of wine. To obtain it, a hole is bored in the stem, in spring, in an oblique direction, one or two inches deep, and a small tube is introduced to carry the sap into a vessel. From a strong stem, there often flows as much as from four to six quarts in a day. If the hole is again closed up each
time with a wooden plug, covered over with clay or resin, and the tapping is annually renewed in the same place, the tree sustains very little injury. B. sap is very beneficial in diseases of the kidneys and in cases of urinary calculus. It contains more than 2 per cent of sugar.—The white B. of North America (B. populifolia) very nearly resembles the common B., but is of much less value. It is found as far s. as Pennsylvania. The wood is scarcely used.—The black B. of the same country (B. nigra), also sometimes called red B., and very similar to the common B., produces very hard and valuable timber. It attains the height of 70 feet. It is not found further n. than New Jersey. The bark is of a dark color, the epidermis in the younger trees reddish.—But the name black B. is also given to another species found in the more northern parts of North America, and sometimes called the sweet B. or cherry B. (B. lenta), also a tree of '70 ft. or upwards in height, and of which the timber is fine-grained, and valuable for making furniture, and for other purposes. Its leaves, when bruised, diffuse a sweet odor, and, when carefully dried, make an agreeable tea. It is remarkable that this tree has been little planted in Britain.—The yellow B. of North America (B. excelsa) is a tree of 70 to 80 ft. high, destitute of branches for 30 to 40 ft., remarkable for its large leaves, which are 3f in. long, and for the brilliant golden yellow color of the epidermis. It is found in Nova Scotia, New Brunswick, Maine, etc. Its timber is used in ship-building. The young saplings of all these American species are much employed for making hoops for casks.—The paper B. (11. papyracea) is found in the northern parts of North America. It attains the height of 70 feet. The bark of the young trees is of a brilliant whiteness. The bark is capable of division into very thin sheets, which have been used as a substitute for paper. It is used by the Indians for canoes, boxes, buckets, baskets, tgc. 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. The wood is used for the same purposes with that of the common B.—The mountainous districts of India produce several species of this genus. Thin, delicate plants of the bark of B. bhojputtra, a native of the mountains of Kinnaon, are used for lining the tubes of hookahs, and are airried in great quantities to the plains of India for this purpose. They were formerly used instead of paper for writing. B. acuminata, a native of the mountains of Nepaul, is a tree 50 to GO ft. high, covered with branches from the base, and of an oval form. Its wood is strong and durable.—The dwarf B. (B. nano) is a mere bushy shrub, seldom more than 2 or 3 ft. 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 in some parts of the highlands of Scotland. It is interesting because of its uses to the Laplanders and other inhabitants of very northertr 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 Terra del Fuego.