in botany: A genus of the pentandria order, belonging to the monocæa clas of plants. The male flowers have no calyx; the corolla is quinquepartite; the stamens are five filaments. There are female flowers on the same plant; these have no calyx nor corolla; the pericarpium is a very small oblong, bivalve, monispermous capsule; the seeds single and egg-shaped.