Fls 4-merous; hypanthium campanulate; sep triangular; intersepalar appendages wanting; pet none; stamens (2-)4, included; ovary imperfectly 2-locular; style very short or none; disk wanting; capsule globose, indehiscent; annual amphibious herb with narrow, opposite lvs and minute greenish fls solitary in the axils. Monospecific.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.