Hypanthium obconic to hemispheric, armed above with hooked bristles, becoming indurate and 10-grooved at maturity; sep spreading at anthesis, later incurved at base and connivent above, forming a beak on the fr; pet 5, yellow, small; stamens 5-15; ovaries 2, concealed within the hypanthium, ripening into achenes; style terminal; perennial herbs from stout rhizomes, the 3-many large lfls of the pinnately compound lvs interspersed with much smaller ones; stipules foliaceous, usually deeply toothed or laciniate; fls in a long, interrupted, spike-like raceme, the short peduncle subtended by a laciniate bract, the very short pedicels by a pair of 3-lobed bractlets. All our spp. fl July-Sept. 15, N. Temp.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.