Plants perennial; rhizomes elongate, knotted, rather stout. Culms sometimes in tufts, erect, stout to slender or almost filiform, 20-70 cm, glabrous or hairy, especially on angles distally. Leaves: sheaths sometimes purplish, not or scarcely winged, weakly ribbed, densely pubescent or glabrous; contra-ligules subrotund to triangular, short; blades linear, keeled, obtuse, shorter than, equaling, or overtopping culm, 1-7 mm wide, ciliate or glabrous. Inflorescences terminal and axillary, fasciculate, 0.5-2.5 cm; clusters few to many flowered, 5-10 mm wide, each with 2-4(-5) spikelets; axillary clusters sometimes on short erect to slender filiform peduncles; bracts subtending inflorescence leaflike, awl-shaped, to 15+ cm, often appearing to be continuation of culm, conspicuously ciliate or glabrous. Spikelets bisexual and staminate, 4-8 mm; staminate scales lanceolate, membranous; pistillate scales ovate-acuminate, midrib conspicuous. Achenes whitish or often brownish gray, globose, 2-3 mm, base constricted, trigonous, apex usually umbonate, tuberculate or verrucose, rarely smooth, papillate at base; hypogynium golden brown, obtusely 3-angled border, supporting 3 yellowish, globose, spiculose or pulverulent, entire or 2-lobed tubercles.
Erect from knotty rhizomes, 3-8 dm; lvs glabrous or hairy, long-attenuate, the larger 2-7 mm wide; cymes 2-3 and approximate or solitary, short-peduncled or sessile, 1-3 cm; pistillate scales ovate, acuminate or short-awned, glabrous or hairy, the prominent midrib projecting as a wing-like keel toward the base; achene globose, white, roughly papillose, (1.5-)2-3 mm thick, minutely apiculate; hypogynium with 3 prominent, transversely ellipsoid tubercles, each often ±2-lobed. Damp sandy soil and pine-barrens; se. Va. to Fla., Tex., and Cuba, n. in the interior to Mo. (S. elliottii)
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.