Fls typically 4-merous; hypanthium globose or campanulate, usually with small intersepalar appendages; sep short; pet present or not, equaling or barely surpassing the sep; stamens 4(8); ovary imperfectly 2-4-locular; disk wanting; capsule rupturing irregularly, not striate; glabrous annuals of wet places, with narrow, sessile, opposite lvs and inconspicuous, bibracteolate fls in small axillary cymes of(1-)3-15. 25, mainly tropical.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.