Stems to 50 cm × 0.1--0.7 mm. Leaves 6--10.5 cm; blade 0.3--0.5 mm, apex ± obtuse. Inflorescences: peduncles with 0--3[--4] coils, 0.5--16.5 × 0.5 mm. Flowers: pistils 4--8. Fruits 1.8--2 × 0.7--1.5 mm; gynophore 1.2--1.9 cm; beak terminal, slightly recurved, 0.6--1 mm. 2n = 16. Flowering spring--fall. Shallow waters of brackish streams, ditches, and lakes along ocean shore; 0--200 m; St. Pierre and Miquelon; B.C., N.B., Nfld. and Labr. (Nfld.), N.S., Ont., P.E.I., Que., Sask.; Ala., Alaska, Calif., Conn., Del., Fla., Ga., La., Maine, Md., Mass., Miss., N.H., N.J., N.Y., N.C., Oreg., R.I., S.C., Tex., Va., Wash.; coastal Mexico; West Indies; Bermuda; Central America; South America; Eurasia; Africa; Australia. No specimens have been seen from Washington, D. C., but the species is to be expected there.
. Stem to 8 dm; lvs 3-10 cm נ0.5 mm; fr 2-3 mm; 2n=14, 16, 20, 24, 28, 40. Interruptedly cosmopolitan; along both coasts of the U.S. in saline or brackish (rarely truly marine) water, and scattered inland in saline or brackish (rarely fresh) water. Highly variable, and by some authors divided into several apparently confluent spp. or vars.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.