the poplar, in botany, a genus of the dioecia octandria clas. The corolla of the male is turbinated, oblique, and entire; the stigma of the female is quadridid; and the capsule has two cells, containing many papous seeds. There are five species, three of them natives of Britain, viz. the alba, or white poplar; the nigra, or black poplar; and the tremula, or trembling poplar, or asp.