BETULA, the birch-tree, in botany, a genus of plants of the Monoecia Tetran idria class. The male flower is amentace ous, formed of a number of monopetalous floscules, each of which is divided into four parts. In the female flower the ca lyx is lightly divided intg three segments: the fruit is a cylindric cone, and the seeds are on each side edged with a membrane. The alder, B. alnus, as well as the B. al ba, belongs to this genus; but of all the species, we shall notice only the latter, or common birch-tree, which is known at first sight by the silvery colour of its bark, the smallness of the leaves, and the lightness and airiness of the whole ap pearance. It is of rather an inferior size among the forest tram. The branches are alternate, sub divided, very pliant and flex ible, covered with a reddish brown or rus set smooth bark, generally dotted with white. Leaves are alternate, bright green, smooth, shining beneath, with veins cross ing like the meshes of a net; the petioles are half an inch or more in length, smooth, grooved above, and at the base are ovate green glands. The birch is a native of Europe, from Lapland to Italy, and of Asia, chiefly in mountainous situations, flowering with us in April and May. The twigs are erect in young trees, but being slender and pliant, they are apt to become pendent in old ones: hence there is a va riety, B. pendula, as beautiful as the weeping willow. Another variety, nam. ed from Dalecarlia, where it is found, has leaves almost palmate, with segments toothed.
The B. alba, though the worst of tim ber, is highly useful for articles of small manufactures, as ox-yokes, bowls, dishes, ladles, and divers other domestic uten sils. In America, they make their canoes, boxes, buckets, dishes, &c.from the birch: from an excrescence or fungus they form excellent touch-wood, and being reduced to powder, it is reckoned a specific for the piles. It is used as fuel, and will
bear being burnt into excellent charcoal. The inner silken bark, which strips off of itself almost annually, was formerly used for writing, before the invention of paper. In Russia and Poland the coarser bark is used instead of tiles or slates for the cov ering of houses; and in almost all coun tries the twigs have been used by peda gogues to keep their pupils in order, and to maintain diligence and discipline in the schools; and also for brooms used in do mestic economy. The bark is used in processes of dyeing; and in Scotland for tanning leather and making ropes. In Kamtschatka they form the bark into hats and drinking-cups.
The vernal sap of the birch-tree is made into wine. In the beginning of March, while the sap is rising, holes must be bored in the body of the tree, and sets made of elder placed in them to con vey away the liquid. If the tree be large, it may be tapped in several places at a time, and thus, according to the number of trees, the quantity of liquid is obtain ed. The sap is to be boiled with sugar, in the proportion of four pounds to a gal lon, and treated in the same way as other made wines. One great advantage at, taching to the birch is, that it will grow on almost any barren ground : upon ground, says Martyn, that produced no, thing but moss, birch trees have succeed ed, so as to produce at least 20s. per acre per ann. The broom-makers are constant customers for birch, in all places within 20 miles of the metropolis, or where wa ter carriage is convenient; in other parts the hoop-benders are the purchasers; but the larger trees are consumed by turn ers, and the manufacturers of instruments of husbandry.