Plants perennial; rhizomes soft, longer internodes 2–4 cm, cortex loose, scales fugaceous, 6 mm, thinly membranous and translucent. Culms not rooting at tips, terete, 10–40 cm, soft to firm, smooth. Leaves: distal leaf sheaths proximally brownish or sometimes reddish, distally stramineous to green. Spikelets ovoid to oblong-subcylindric, 4–12 × 2–3.5 mm, apex acute to rounded; proximal scale empty, clasping 1/2 of culm, like floral scales; subproximal 1 or 2 scales often empty; floral scales 20–100, 10 per mm of rachilla, entirely stramineous or sometimes red-brown, ovate, (1.5–)2–2.5 × 1.5 mm, apex broadly rounded, entire. Flowers: perianth bristles (5–)6(–8), brown, stout, the longer equaling achene or tubercle, retrorsely spinulose; stamens 3; anthers brown, 1 mm. Achenes falling with scales, obovoid, angles keeled, 0.8–1 × 0.7–0.8 mm, apex with short neck. Tubercles whitish to brown, mammillate to pyramidal, 0.2–0.3 × 0.3–0.35 mm, 1/3 or less as wide as achene.
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Cespitose perennial, sometimes also rhizomatous; stems slender, erect, 1-3 dm; sheaths very oblique, the projecting lobe twice as long as its diameter; spikelet ovoid, 2-10 mm; scales broadly rounded above, cartilaginous, pale brown, closely appressed; bristles dark brown, longer than the achene; style trifid; achene brown, trigonous, 1 mm; tubercle depressed-pyramidal, a third as wide and a fourth as long as the achene. Brackish marshes along the coast; Md. to Mex.; Bermuda.