Herbs, annual, cespitose. Culms trigonous to roundly trigonous, (0.5-)5-25(-105) cm × 1-2.5(-7.5) mm, glabrous. Leaves flat to inversely W-shaped, 5-25(-90) cm × 2-5(-11) mm. Inflorescences: spikes 1-3(-6), rather densely cylindric-ovoid, (4-)10-30(-45) × (6-)10-16(-23) mm; rays 2-6(-12), 1-8(-28) cm; bracts (3-)5-7(-11), horizontal to ascending at 30°, inversely W-shaped, (3-)10-20(-70) cm × 1-3(-12) mm; rachilla persistent, at maturity becoming laterally free, remaining firmly attached proximally, wings 0.3(-0.4) mm wide. Spikelets (20-)40-80, linear, quadrangular, 3-8(-11) × 1-1.5 mm; floral scales deciduous, 6-16(-30), appressed, laterally light brown with reddish speckles, medially greenish, laterally ribless, medially 3-ribbed, oblong-ovate to obovate, quadrangular to subterete, 1.3-1.5 × 0.8-1.2 mm, apex obtuse, mucronulate. Flowers: anthers 0.2-0.3 mm, connectives 0.1 mm; styles 0.7-0.8 mm; stigmas 0.4 mm. Achenes light grayish to brown, sessile, ovoid, 0.4-)0.7-1 × 0.4-0.6 mm, apex rounded, apiculate, surfaces glabrous. Fruiting summer. Emergent shorelines; 0-1500 m; Man., Ont.; Ala., Ariz., Ark., Calif., Conn., Del., D.C., Fla., Ga., Ill., Ind., Iowa, Kans., Ky., La., Maine, Md., Mass., Mich., Minn., Miss., Mo., Nebr., Nev., N.H., N.J., N.Mex., N.Y., N.C., N.Dak., Ohio, Okla., Oreg., Pa., R.I., S.C., S.Dak., Tenn., Tex., Utah, Va., Wash., W.Va., Wis.; Mexico (Baja California).

Notes: Stems solid and terete, trigonious.Scales of inflorescence 2-ranked.Leaf arrangement 3-ranked.Leaves 3-5 nerved and scabrous on margins and midrib. References: Kearney & Peebles; Arizona Flora. McDougall; Seed plants of N. Arizona.