Eleocharis palustris (L.) Roem. & Schult.

Plants perennial, mat-forming; rhizomes evident, long, 1.5–4.5 mm thick, firm to hard (or soft), cortex persistent, longer internodes 10–35 mm, scales usually persistent, 6–20 mm, membranous, sometimes slightly fibrous. Culms terete or slightly compressed, often with 8–30 blunt ridges when dry, 30–115 cm × 0.5–5 mm, firm to soft, internally spongy. Leaves: distal leaf sheaths persistent or sometimes disintegrating, often splitting adaxially, red or blackish proximally, green or red distally, not inflated, not callose, membranous to papery, apex broadly obtuse to acute, tooth absent. Spikelets ovoid to lanceoloid, 5–25 × 3–7 mm, apex acute to obtuse; proximal scale clasping 2/3 or sometimes 3/4 of culm, entire; subproximal scales 1–2, empty; floral scales often spreading in fruit, 30–100, 4–8 per mm of rachilla, brown, midrib regions mostly stramineous to green, ovate to lanceolate, 3–5 × 1.5–2.5 mm, apex entire, acute or subacute, often carinate in distal part of spikelet. Flowers: perianth bristles 4(–5), sometimes absent, medium brown to stramineous, slender to stout, much shorter than achene to equaling tubercle, rarely to 2 times as long as achene; stamens 3; anthers dark yellow to stramineous, 1.5–2.2 mm; styles 2-fid, very rarely some 3-fid. Achenes not persistent, stramineous or dark brown, biconvex, angles obscure, obovoid to obpyriform, 1.1–2 × 1–1.5 mm, apex rounded, neck absent or mostly short (to long), smooth at 30X, sometimes finely rugulose at 10–20X and with 20 or more ridges in vertical series. Tubercles brown to whitish, pyramidal to mamillate, as high as wide to 2 times higher, 0.3–0.7 × 0.35–0.7 mm. 2n = 16, 17, 36.

Marshes, ditches and the margins of ponds. Wet meadows, irrigation ditches, springs, seepage areas, freshwater marshes, rivers, and along lakeshores.

Can be grown by divisions or seedlings. Seeds needs scarification.