RAIANIA, in botany: A genus of the hexandria order, belonging to the dioecia class of plants; and in the natural method ranking under the 11th order, Samentaceæ. The male calyx is sexpartite; there is no corolla. The female calyx as in the male, without any corolla; there are three styles; the fruit is roundish with an oblique wing, inferior. There are three species, the hastata, cordata, and quinquefolia.