Stoloniferous perennial, the basal part of the stem prostrate and rooting, the rest ±erect, 3-10 dm, glabrous or nearly so, freely and slenderly branched; cauline lvs lanceolate, 3-10 cm נ5-15 mm, tapering to a short petiole or petiolar base, with conspicuous secondary veins; fls sessile, 4-merous; sep 1.5-2 mm; pet none; anthers ca 0.3 mm; fr glabrous or minutely puberulent, cylindric or obscurely 4-grooved, 4-8 mm; 2n=32. Wet or muddy soil or shallow water; coastal plain from se. Va. to Fla. and Tex., n. in the interior to s. Ind. and Kans. July-Sept.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.