Five or six species of this curious genus have been introduced, all found wild in western N. America. They are evergreen or sub-evergreen shrubs and small trees, with alternate leaves and small axillary flowers on short stalks, either solitary or in few-flowered clusters. They have no petals, but a five-lobed calyx, and numerous (fifteen to thirty) stamens. The most distinctive feature of the genus is the small, hard, slender fruit, terminated by the long, persistent style, which is plumed with long, white, silky hairs. The genus has been revised by F. L. Martin in Brittonia, Vol. 7, pp. 91-111 (1950).