Sep 4 or 5, broadly obovate, caducous; pet and staminodes none; stamens very numerous, the filaments widened distally and often wider than the short, oblong anthers; pistils several, small; styles short, subulate; fr a 4- nerved, thin-walled, 1-seeded, dehiscent utricle; stout perennials with large, alternate, palmately divided lvs and broadly rounded, corymbiform clusters of small white fls. Monospecific.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.