Herbs, perennial, rhizomatous. Culms trigonous, (12-)30-80(-90) cm × 0.7-1.7 mm, glabrous or nearly so. Leaves flat to V-shaped, 20-45 cm × 2-4 mm, margins and keel minutely scabridulous. Inflorescences: spike 1, loosely ovoid to ovoid-ellipsoid, (1.5-)2.5-7 × (1-)1.5-3.5 cm; rays 1-4, 1-15 cm; rachis 1-2 cm; bracts 2-4, oblique or ascending, 1-15(-24) cm × 0.4-3.5 mm, keel, margins scabrid; rachilla ± deciduous, wingless. Spikelets (3-)8-40, linear, compressed-quadrangular, 8-18 × (2.4-)2.8-4 mm; floral scales deciduous, (2-)4-12, laterally light brown to reddish brown, medially green or light brown, laterally 2-3-ribbed, oblong-ovate, 1.6-2.6 × (1.5-)1.6-2.2(-2.4) mm, apex obtuse, sometimes mucronulate, medially glabrous. Flowers: anthers 0.4-0.6 mm; styles 0.3-0.6 mm; stigmas 0.6-1 mm. Achenes brownish, stipitate, ellipsoid, 1.6-2 × (0.7-)0.9-1 mm, stipe whitish, 0.1-0.2 mm, apex obtuse, slightly apiculate, surfaces papillose. Fruiting summer. Arroyos, riverbanks, clearings in montane forests; 100-1300 m; Ariz., Tex.; Mexico.

Plant: Perennial graminoid 20-90 cm; stems three-sided