Proc. Amer. Acad. Arts 34: 493, figs. 27–29. 1899.
Culms 20–35 cm × 0.3–1 mm. Leaves: apex of distal leaf-sheath subacute to narrowly acute, tooth to 0.3 (–1.1) mm. Spikelets narrowly lanceoloid, 3–12 × (1–) 2–2.5 (–4) mm, apex acute; floral scales 25–100, 10–12 per mm of rachilla, orangebrown to stramineous, ovate, 1.5–2 × 1 mm, midribs mostly keeled, apex acute or narrowly rounded in proximal part of spikelet. Flowers: perianth bristles 6–7, brown, stout, the longest equaling or exceeding tubercle; stamens 2–3; anthers brown, 0.3 mm; styles 2-fid. Achenes 0.9–1.1 × 0.6–0.8 mm. Tubercles deltoid, 0.25–0.5 × 0.5–0.7 mm, 1/2–2/3 as high as wide, 1/4–1/2 as high and 2/3–4/5 as wide as achene. 2n = 10.
Phenology: Fruiting summer to fall.
Habitat: Fresh shores, stream beds, pine woods, disturbed places
Elevation: 0–400 m
Ark., Calif., Kans., La., Mo., Okla., Tenn., Tex.
Some collections of Eleocharis lanceolata from Tennessee appear to be intermediate with E. obtusa. The California record is an introduced rice-field weed collected in 1949.