Herbs, perennial, cespitose, shortly rhizomatous, coarse, viscous. Culms round to roundly trigonous, 15-80 cm × 2-4 mm, glabrous. Leaves: adaxial face concave, becoming trigonous apically, 15-75 cm × 1-4 mm, margins involute. Inflorescences: spikes ovoid, 10-20 mm wide; rays 3-8(-10), 0.5-12 cm; 2d order rays 0-3, 1-3 cm; bracts 3-7, horizontal to vertical, 2.5-5.5 cm × 1-4 mm, margins involute; 2d order bracts 0-3, 1-3 cm; rachilla persistent, wingless. Spikelets 3-20(-30), beige to greenish or reddish brown, strongly compressed, oblong-ellipsoid to oblong-lanceoloid, 3-15 × 2.5-3.5 mm; floral scales deciduous, 6-22, laterally pale greenish white to stramineous or reddish brown, medially pale green to yellowish green, laterally 2-ribbed, medially 3-5-ribbed, broadly ovate, (2-)2.8-3.6 × 2.4-2.6 mm, apex with slightly excurved mucro 0.2-0.3 mm, apically scabrid. Flowers: anthers 0.6-1.4 mm; styles 1.2-1.5 mm; stigmas 1-1.5(-3) mm. Achenes dark reddish brown to black, stipitate, obovoid, faces concave, flat or subtly convex, (1.4-)1.8-2 × 0.9-1 mm, base cuneate, stipe (sometimes absent) spongy, 0.1-0.2 × 0.2-0.4 mm, apex truncate, apiculate, surfaces coarsely papillose. Fruiting summer. Ditches, damp pastures, pond shores, riverbanks; 0-500 m; Fla., La., N.Mex., Tex.; Mexico; Central America; South America.