Isolepis planifolia Sprengel, Neue Entd. 3: 10. 1822; Baeothryon planifolium (Sprengel) Sojak; B. verecundum (Fernald) Á. Löve & D. Löve; Eleocharis planifolia (Sprengel) Nees; Scirpus planifolius Muhlenberg 1817, not Grimm 1767; S. verecundus Fernald

Plants densely cespitose; rhizomes absent. Culms trigonous, 10–40 cm, scabrous proximal to inflorescence. Leaves: basal sheaths brown; distal leaf sheaths concave at mouth; blades 10–400 × 0.8–2 mm, equaling or exceeding culms at flowering and fruiting. Inflorescences: spikelets 3–8-flowered, 4.1–5.2 × 1.5–2.1 mm; bracts equaling spikelets, 3.7–6 mm, apex awned, awn to 3 mm. Spikelets: scales orange-brown to dark brown, midribs excurrent, apex mucronate. Flowers: perianth bristles 3–6, brown, terete, nearly equaling achenes, scabrous; anthers 1–1.5 mm. Achenes compressed trigonous, 1.5–2 × 0.7–1.1 mm.

Fruiting summer (Jun–Jul). Mesic to dry hardwood forests, usually with oak component, often on hillsides; 50–900 m; Ont.; Conn., Del., D.C., Ill., Md., Mass., Mo., N.J., N.Y., Ohio, Pa., R.I., Vt., Va., W.Va.