QUERCUS, in botany, the oak tree, a genus of the Monoecia Polyandria class and order. Natural order of Amentacew. Essential character: male, calyx com monly five-cleft ; corolla none ; stamina five to ten : female, calyx one-leaved, quite entire, rugged ; corolla none ; styles two to five ; seed one, ovate. There are twenty-six species, and many varieties ; Q. robur, the common oak, attains to a great size, particularly in woods ; singly, it is rather a spreading tree, sending off, horizontally, immense branches, which divide and subdivide considerably ; the trunk is covered with a rugged brown bark ; leaves alternate, oblong, broader towards the end, the edges deeply sinu ate, firming obtuse or rounded lobes, of a dark green colour, five inches in length, two and a half in breadth, they are deci duous, but often remain on the tree till the new buds are ready to burst. The male flowers come out on aments, in bundles, from the buds, alternately and singly from the axils of the leaves ; they are pendu lous, cylindrical, consisting of yellow, short, roundish, scattered bundles of an thers ; above the males the aments of fe male flowers come out, each composed of thi ee or four small reddish florets, placed alternately, having at the base little red dish scales, which afterwards become the cup, forming the rugged external surface of it ; acorn ovate, cy lindrical, coriaceous, very smooth, except at the base, where it appears as if rasped, one-celled, valveless, received at bottom in a hemispherical cup, tubercled on the outside ; the germ is three-celled, with two embryos in each cell, fastened to the base. The wood of the oak, when of a good sort, is well known to be hard, tough, tolerably flexi ble, not easily splintering, strong without being too heavy, and not easily admitting water ; for these qualities it is preferred to all other timber for building ships ; it would be difficult to enumerate all the uses In which it may be applied. Oak
saw-dust is the principal indigenous ye getable used in dyeing fustian ; all the va rieties of drabs and different shades of brown, are made with oak saw-dust, vari ously managed and compounded. Oak apples are also used in dyeing, as a substi tute 'Or galls. See GALLS.
Q. sober, cork-barked oak, or cork tree: there are two or three varieties of this species, one with a broad leaf, a second with a narrow leaf, both ever green ; and one or two which cast their leaves in au tumn; the broad-leaved evergreen is the most common ; the leaves of this are en. tire, about two inches long, and an inch and quarter broad, with a little down on their under sides, oh short fbotstallts ; these leaves continue green through the winter till May, when they generally fall offjust before the new leaves come out ; the acorns are very like those of the com mon oak. The exterior bark is the cork, which is taken from the tree every eight or ten years ; there is an interior bark which nourishes them, so that stripping off the outer bark is so far from injuring the trees, that it is necessary to continue them ; for when the bark is not taken off; they seldom last longer than fifty or sixty years in health ; whereas trees which are barked every eight or ten years, will live one hundred and fifty years, or more.
The uses of the cork are well known, both by sea and land ; the poor people in Spain lay broad planks of it by their bed side to tread on, as great persons use Tur key and Persian carpets, to defend them from the floor ; they frequently line the walls and the inside of their houses, built of stone, with this bark, which renders them warm, and corrects the moisture of the air. This tree is a native of the south of Europe.