botany, a genus of the dioecia tetran-dria clas. The calyx of the male has two segments; and the corolla is wanting. The calyx of the female consists of two segments; it has no corolla; but one stylus; and the berry contains many seeds. There are three species, only one of which, viz. the rhamnoides, fallow-thorn, or sea buck-thorn, is a native of Britain.