Annuals. Roots fibrous. Culms densely tufted, 5-50 cm tall, compressed 3-angled, smooth, with several leaves basally. Leaves several, usually shorter than culm to rarely longer; sheath usually reddish brown, short; leaf blade 2-4 mm wide or less, flat, apical margin denticulate. Involucral bracts 2-5, leaflike, longer than inflorescence, subspreading. Inflorescence a simple anthela; rays 3-5, mostly to 4.5 cm to sometimes very short and inflorescence a capitulum, each with 4-12 or more spikelets congregated into a short spike or nearly a capitulum. Spikelets radially spreading, narrowly ovoid to narrowly oblong-ovoid, 0.5-1.8 cm × 2.5-3 mm, 6-24-flowered; rachilla straight, 4-angled, wingless. Glumes straw-colored, brownish yellow, or blackish brown on both surfaces but middle yellowish green, slightly laxly imbricate, ovate, ca. 2 mm, membranous, medially 3-5-veined, often distinctly furrowed on both sides of keel, margin dark blood-red to dark brownish red, apex obtuse. Stamens (2 or)3; anthers linear, 0.7-1 mm. Style long; stigmas 2, exserted, slender. Nutlet black at maturity, globose-obovoid to broadly ellipsoid, 1-1.3 mm, 1/2-3/5 as long as subtending glume, biconvex, slightly turgid, minutely punctate. Fl. and fr. Jul-Dec. 2n = 48, 50.