Plants usually annual, tufted, sometimes mat-forming via proliferating and arching inflorescences (stoloniferous), sometimes entirely vegetative; rhizomes absent. Culms often ascending or arching, quadrangular or broadly elliptic, 2–40 cm × 0.1–0.4(–0.6) mm, soft. Leaves: distal leaf sheaths persistent or disintegrating, pale brown, green or red-brown, streaked or mottled red-brown or purple, translucent, membranous, apex narrowly acute. Spikelets: basal spikelets absent; often proliferous, ovoid to ellipsoid or lanceoloid, terete, 2–10.7 × 1–2 mm, apex acute; proximal scale empty, persistent, amplexicaulous, dissimilar to floral scales, often longer, often resembling an involucral bract, ovate to lanceolate, midrib markedly thickened and broad and often prolonged beyond lamina; subproximal scale with flower; floral scales spiraled, colorless, whitish, or pale brown, streaked or mottled red-brown or purple, midribs green and red-brown or green and purple, ovate to elliptic, 0.8–1.5 × 0.4–0.8 mm, membranous, midrib obscure to prominent. Flowers: perianth bristles present or sometimes apparently absent; stamens 3; anthers 0.15–0.35; styles 3-fid. Achenes whitish to olive or pale brown, sometimes spotted olive or red-brown, obovoid, trigonous (or subterete), angles prominent, 0.55–0.8 × 0.3–0.5 mm, apex constricted proximal to tubercle, smooth. Tubercles green or pale brown to red-brown, trigonous.
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Cespitose annual with slender stems to 3 dm (or more elongate in water); sheaths oblique at the orifice; spikelet ovoid or oblong, 2–7 mm, several-fld; scales rounded above, pale at the margin or throughout; bristles half to nearly as long as the achene; style trifid; achene obovoid, trigonous, pale greenish-gray to nearly white, 0.6–0.8 mm; tubercle minute, depressed-pyramidal. Acid swamps near the coast; Conn. to Fla. and Tex.; Ind. and Tenn. (E. torreyana; E. brittonii Svenson, coarser, to 5 dm, with flatter tubercle, perhaps to be held as distinct)
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