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.