Enum. Pl. 2: 328. 1805.
Herbs, perennial, cespitose, bases cormose; rhizomes knotted, beaded. Culms trigonous, 15–48 cm × 0.4–1 mm, glabrous. Leaves flat, 10–30 cm × 0.5–2 mm. Inflorescences: spikes rather densely ovoid, 1–3.5 cm; rays 0 (sometimes 1–4), 1–6 cm; rachis 1–4 mm; bracts 3–4, horizontal to slightly reflexed, flat, 6–25 cm; rachilla ± deciduous, wingless. Spikelets 25–60, compressed, oblong-lanceoloid, 5–12 × 2.2–3.5 mm; floral scales deciduous, 5–15, yellowish to yellowish brown, laterally 4–5-ribbed, oblong-ovate, 2.6–3.6 × 1.4–2 mm, margins loosely spreading or clasping achene. Flowers: anthers 0.8–1 mm; styles 1 mm; stigmas 1.5–2.5 mm. Achenes dark grayish brown, sessile, narrowly oblong, 1.8–2.2 × 0.5–0.8 mm, apex obtuse, apiculate, surfaces puncticulate.
Phenology: Fruiting summer.
Habitat: Well-drained, open roadsides, fields, pine barrens, dunes
Elevation: 0–200 m
Ala., Fla., Ga., La., Md., Miss., N.C., S.C., Tex., Va.
Cyperus filiculmis has long been treated within a broader and more widely used concept of C. filiculmis (C. lupulinus); see B. G. Marcks (1974)