Herbs, annual, cespitose. Culms roundly trigonous, (10-)20-30(-45) cm × 0.4-1.2 mm, distal 1/2 glabrous or infrequently scabridulous. Leaves 2-6(-8), V-shaped or flat, 8-12(-16) cm × 1-2(-4) mm. Inflorescences: heads hemispheric, 7-12(-15) mm diam.; rays 1-3(-5), 0.5-2 cm; bracts 3-6, longest erect to ascending, flat to V-shaped, (1.5-)3-12(-25) cm × 1-2.5(-3.5) mm. Spikelets (15-)25-50(-75), ovoid, compressed, 4-7 × 2-3 mm; floral scales 8-20(-35), laterally yellowish, yellowish green, or light reddish brown, medially light brown or greenish brown, 2-keeled, subtly 1-ribbed, ovate-lanceolate, 1-2 × 1-1.4 mm, apex acute, mucronate, straight to excurved, glabrous or sparsely scabridulous. Flowers: stamen 1; anthers 0.5 mm; styles 0.8-1.1 mm; stigmas 0.5 mm. Achenes brown, stipitate, broadly ellipsoid, abruptly contracted to base, 0.8-1.1 × 0.3-0.4 mm, stipe 0.1 mm, apex acute, tapering to slender beak formed of persistent style base, surfaces papillose. Fruiting summer-fall (Jul-Oct). Wet, often sandy shores and damp, disturbed soils; 0-1500 m; Ala., Ariz., Ark., Calif., Colo., Ill., Ind., Iowa, Kans., Ky., La., Mich., Minn., Mo., Mont., Nebr., N.H. (introduced?), N.Y. (introduced?), N.C., N.Dak., Ohio, Okla., Oreg., Pa. (introduced?), S.Dak., Tenn., Tex., Utah, Va., Wash., Wyo.; Mexico (Coahuila, Tamaulipas).