Herbs, annual or perennial, cespitose, slender. Culms to 40 cm, wiry. Leaves ¼-1/2 length of culms; sheaths stramineous to tan or brown, glabrous or scabrid on ribs; blades spreading to ascending, filiform, 0.5 mm wide, involute, margin glabrous or scabrid, abaxially glabrous or hirtellous. Inflorescences terminal, in simple or compound anthelae; scapes wiry, coarsely ribbed, glabrous or strumose-puberulent; longer primary involucral bracts with setaceous blades exceeding or exceeded by inflorescence. Spikelets red-brown to dark brown, lanceoloid to cylindric, longer than wide, 2-6 mm; fertile scales broadly ovate, keeled, 1-1.3 mm, apex acute, abaxially puberulent, midrib included or excurrent as mucro. Flowers: stamens 2-3; anthers narrowly oblong, 0.8-1 mm. Achenes mostly waxy gray, trigonous, obovoid, 0.8-1.5 mm, faces evenly papillate, finely rugulose or level; tubercle a small, dark, compressed-conic button.
Tufted, to 4 dm; lvs up to half as long as the culms, slender, to 0.5 mm wide, often involute; spikelets lance-ovoid, 2-6 mm, few-fld, in umbelliform cymes; scales ovate or broadly ovate, curved-keeled; anthers 2 or 3, 1 mm; achene obovoid-trigonous, 1 mm, grayish or grayish-blue, finely papillate; tubercle minute, depressed-globose; 2n=60. Sandy places; se. Va. to Fla. and Tex. and n. to Tenn.; Cuba. Two ecologically differentiated vars. of nearly coextensive range. Var. ciliatifolia, of less extreme habitats, often weedy, is annual, with few spikelets in a simple or subsimple infl that is seldom surpassed by the longest bracts; the veins and edges of the lvs are usually hispidulous, and the midrib of the scale is only slightly or not at all excurrent. Var. coarctata (Elliott) Kral, usually in ant-hills with longlf pine, is ±perennial, with more numerous spikelets in a more compound infl that is commonly surpassed by the longest bract; the lvs are mostly smooth except for the scabrous-tuberculate to hispidulous edges, and the midrib of the scale is usually shortly mucronate-excurrent. (B. coarctata)
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.