Sep and pet each 2-4; stamens as many (in our spp.) or twice as many as the sep; ovary 2-4-locular, the placentas axile or basal-axile; seeds several per cell, cylindric, minutely areolate; small aquatic annuals with inconspicuous axillary fls and thin- walled frs. 20, widespread.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.