Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.
Genus Description - Subdioecious; staminate fls with short, broadly obconic hypanthium; tep usually 5; disk prolonged into as many short, glandular lobes, bearing stamens in the sinuses, the pistil infertile; fertile fls with longer hypanthium and smaller anthers on shorter filaments, the style short and stout, the stigma capitate; fr a pyriform to subglobose drupe; trees or shrubs with thin, alternate lvs and small greenish fls in peduncled terminal racemes; 2n=38. 4, the others in e. Asia.