Eleocharis nigrescens Kunth

Plants usually annual, tufted, not stoloniferous; rhizomes absent. Culms sometimes ascending, subterete, elliptic, or polygonal, (1–)3–7.5(–9) cm × 0.2–0.5 mm, very soft. Leaves: distal leaf sheaths persistent or disintegrating, colorless, stramineous or green, spotted red-brown to purple, membranous, apex narrowly acute. Spikelets: basal spikelets absent; never proliferous, ovoid or ellipsoid, terete, 2–4.7(–8.5) × 1–2 mm, apex acute to blunt; proximal scale empty or with flower, persistent, clasping 1/2 of culm, similar to floral scales (but 1.1–1.7 mm, midrib region broadly green); subproximal scale with a flower; floral scales spiraled, 10–30(–100), 10–16 per mm of rachilla, colorless, whitish, or pale brown, mottled red-brown to purple, midribs pale brown or green, ovate or elliptic, 1–1.2 × 0.45–0.6 mm, membranous, midrib prominent, apex rounded. Flowers: perianth absent; stamens 1; anthers 0.2–0.3 mm; styles 3-fid. Achenes colorless (appearing green-brown from enclosed seed) or whitish, sometimes spotted red-brown, obovoid, trigonous, angles prominent, 0.5–0.6 × 0.33–0.4 mm, apex constricted proximal to tubercle, smooth. Tubercles white, gray or pale brown, pyramidal or umbonate, trigonous, 0.1–0.15 × 0.15–0.2 mm.