Culms to 42 cm. Floral scales brown to stramineous. Flowers: perianth bristles vestigial to slightly exceeding achene, rarely longer. Achenes red-brown to dark brown when ripe, 0.4-0.8(-1.1) × 0.3-0.6 mm, apex rarely highly constricted proximal to tubercle. Tubercles 0.2-0.5 × 0.2-0.4 mm. 2n = 30.

Fruiting mid spring-winter. Brackish creeks, canal banks, dune depressions, hammocks, hot springs, irrigation ditches, maritime mud flats, salt marshes; 0-300(-1600) m; Ala., Ariz., Ark., Calif., Fla., Ga., Idaho, La., Miss., Mont., N.C., S.C., Tex., Utah, Va., Wyo.; West Indies; South America.