Fls perfect, 3-merous; sep triangular, persistent and somewhat accrescent; pet none; stamens 3; ovary 3-locular; styles 3, subulate, stigmatose beyond the middle; fr indehiscent, bony, 3-seeded and ±triangular; amphibious or marsh herbs, perennial by a rhizome-like base; stem beset with short, dark spicules; lvs all alternate, at least the submersed ones, when present, deeply pinnatisect; fls small, purplish or greenish, solitary or 2 or 3 together, sessile in the axils of emersed lvs. 2, N. Amer.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.