Fls (3)4(-6)-merous; hypanthium campanulate to globose or urceolate, with (as in our sp.) or without intersepalar appendages; pet present or absent; stamens 4(-6); ovary imperfectly (3)4(-6)-locular; disk wanting; capsule septicidal, (2)3-4-valved, transversely minutely and densely striate; glabrous annuals of wet places, with small, inconspicuous, bibracteolate fls solitary in the axils. 45, mainly Old World tropics.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.