Glabrous perennial with scattered stems from stout creeping roots, somewhat fleshy, prostrate or decumbent, 2-5 dm; lvs linear or linear- oblanceolate, 1-4 cm נ2-5 mm; spikes seldom over 5 cm, the terminal ones usually paired on a peduncle, the lateral usually solitary and sessile or nearly so; cor 2-3.5 mm wide, white with a yellow eye; mature cal spreading; fr depressed-ovoid, 1.5-2.5 mm, soon splitting into 4 nutlets; 2n=26, 28. Native of tropical Amer., established as a weed, especially in saline soil, in s. U.S. n. to Del. and occasionally as a weed farther n. May-Sept. Ours are var. curassavicum. The well marked var. obovatum A. DC. (H. spathulatum) of interior w. U.S., with broader, more oblanceolate or even oblate lvs 6-18 mm wide and with the cor 5-9 mm wide, often with a purple eye, may possibly extend to w. Minn.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.