Ann. Lyceum Nat. Hist. New York 3: 349. 1836.
Plants annual; rhizomes absent. Culms 1–25 cm × 0.2–0.3 mm. Leaves: sheaths green to stramineous or brown; distal blade mostly much longer than sheath, to 5 cm × 0.2–0.5 mm. Inflorescences: involucral-bract 1, 5–25 (–33) mm. Spikelets 1–10 × 1.5–2 mm; scales stramineous to pale orangish, midrib region often greenish, markedly gibbous, prominently to obscurely veined, midrib keeled, finely reticulate at 20X, membranous, hyaline, apex rounded, awned; proximal scale to 2.5 (–5) mm, awn to 2 mm; other scales 1.8–2 × 1–1.2 mm, awn 0.2–0.5 mm. Flowers: anthers 0.2 mm; styles 3-fid. Achenes often falling with and clasped by floral scales, dark orangebrown or often whitish, broadly ellipsoid to obovoid or outline subcircular, nearly equilaterally trigonous, faces concave, 1–1.5 × 0.7–1 mm, papillose at 10–15X, papillae in many vertical rows, often obscured by thin, minutely reticulate, whitish surface layer.
Phenology: Fruiting spring.
Habitat: Wet, often drying, freshwater places in grasslands, rock barrens, open woods, lawns, cultivated fields, waste places
Elevation: 0–800 m
Ala., Ark., Calif., Fla., Ga., Ill., Kans., Ky., La., Miss., Mo., N.C., Okla., S.C., Tenn., Tex.
Isolepis carinata sometimes occurs in mixed populations with the very similar I. pseudosetacea.