Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.
Genus Description - Dioecious, or some fls perfect; staminate fls with obconic hypanthium, the 4 tep each with a tuft of hairs behind and ± adherent to the stamen; pistillate fls with campanulate hypanthium, 4 tep, and shortly conic, 4-lobed style, often also with stamens; fr an ellipsoid, 1- seeded drupe; shrubs with glabrous twigs and foliage, opposite lvs, and small greenish fls, the staminate in slender-pedunculate axillary umbels, the pistillate solitary in the axils. Monospecific.