Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.
Genus Description - Dioecious; fls 5-merous; hypanthium saucer-shaped; sep triangular; pet spatulate to obovate; stamens 15 or more, unequal, vestigial in pistillate fls; carpels 3(4–5), distinct, erect, with divergent styles, capitate stigmas, and several ovules, vestigial in staminate fls; follicles oblong, turgid, ventrally dehiscent; tall, shortly rhizomatous perennial herbs with alternate, exstipulate, 2–3-ternately compound lvs and small white fls in numerous racemes aggregated into a large terminal panicle. Much like Astilbe in aspect, but sharply distinct on floral characters. 10+, N. Temp.