Plants annual, densely tufted; rhizomes present, inconspicuous, erect or ascending, 0.5 mm thick, internodes less than 2 mm, scales disintegrating, 3 mm, membranous-translucent. Culms often arching or recurved or reclining, their spikelets usually all fruiting simultaneously, long to very short in 1 tuft, subterete, 4–40 cm × 0.2–0.5 mm, soft. Leaves: distal leaf sheaths persistent and evident or disintegrating (fugaceous) and not evident, proximally green or stramineous, brown, reddish, or purple, distally stramineous to green or colorless, papery to membranous, apex subacute to acuminate, sometimes with linear blade to 1 mm. Spikelets: basal spikelets absent (often some spikelets subsessile); never proliferous, ovoid, terete, 2–10 × 1–2 mm, apex acute; proximal scale empty or with a flower (usually in the same plant), deciduous or some persistent, amplexicaulous, similar to other scales (except apex sometimes rounded); subproximal scale with a flower; floral scales spiraled, 5–30, 5–6 per mm of rachilla, pale brown to colorless, often spotted brown, ovate, 1.5–2 × 1 mm, thinly membranous to translucent, midribs often green, evident to obscure, apex acute. Flowers: perianth bristles 6–7, pale brown to stramineous or whitish, slender, equaling to exceeding tubercles or rarely rudimentary to less than 1/2 achene length; spinules sparse, retrorse, sharply acute; stamens 3 (sometimes fewer?); anthers 0.2–0.5 mm; styles 3-fid. Achenes golden brown, narrowly obpyriform, proximally markedly narrowed, compressed-trigonous, angles slightly prominent, 0.9–1 × 0.6–0.75 mm, finely reticulate or pitted or papillose at 20–30X, apex usually constricted proximal to tubercle. Tubercles brown, narrowly pyramidal to linear, trigonous, 0.3–0.4 × 0.1–0.25 mm. 2n = 22.
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Densely cespitose; stems reclining or ascending, capillary, very unequal, 5–25 cm; sheaths truncate or somewhat oblique, the projecting lobe acute, no longer than its diameter; scales obtuse or the upper acute, with brown sides, the lowest one empty; bristles pale brown, usually slightly longer than the achene; anthers less than 0.5 mm; style trifid; achene trigonous, light olive or yellowish, 1 mm, the narrow tubercle conic-subulate, a third to half as long; 2n=22. Wet soil; Que. to Minn., s. to Pa., w. Va., Tenn., and Io. (E. macounii)