Herbs, annual, cespitose. Culms trigonous, 5-25 cm × 1-1.5 mm, glabrous. Inflorescences: spikes loosely ovoid, 15-25 mm wide; rays 1-6, 2-7 cm; bracts 2-5, 3-20 cm, ascending; rachilla deciduous, winged. Spikelets 5-30, linear, flattened, 6-22 × 1.5-2.2 mm; floral scales ± deciduous, (4-)8-12, red, reddish purple, or reddish brown, medially green, elliptic, laterally 2-4-ribbed, 2.3-3.1 × 1.2-2 mm, apex acute to obtuse. Flowers: anthers 0.3-0.4 mm; styles 1 mm; stigmas 1.3-1.6 mm. Achenes brown to dark purplish brown, broadly ellipsoid, 1-1.3 × 0.6-0.9 mm, surfaces puncticulate. Fruiting summer. Stream banks, desert washes, arroyos, roadsides; 0 800 m; Ariz., Calif., N.Mex.