Staminate fls in small heads on drooping peduncles, the bracts caducous, the stamens 8-16; pistillate fls usually paired on a short peduncle, concealed by the numerous subulate bracts; ovary 3-locular; fr a sharply 3-angled nut; 1-seeded, borne normally in pairs within the accrescent, 4-valved involucre; trees with straight-veined lvs, a vein running to each tooth; fls appearing with the lvs, the staminate from the lower axils, the pistillate from the upper. 10, N. Temp.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.