Cyperus compressus var. pectiniformis (Roemer & Schultes) C. B. Clarke; C. pectinatus Roxburgh; C. pectiniformis Roemer & Schultes

Herbs, annual, cespitose with fibrous roots. Culms trigonous, (2–)6–15(–35) cm × (0.3–)1–1.8 mm, glabrous. Leaves 1–5, flat to V-shaped, (1–)5–15(–22) cm × (0.5–)1.5–3 mm. Inflorescences: spikes ± digitate, ± globose, 7–40 × 10–20 mm; rays (0–)1–6, 2–12 cm; if absent, inflorescence a sessile cluster of (1–)3–10 spikelets; rachis 2–5 mm; bracts (1–)4–5(–6), ascending, V-shaped, 1–15(–20) cm × 0.5–3.5 mm; rachilla persistent, wingless. Spikelets (1–)3–12(–16), greenish white, linear to linear-lanceoloid, compressed-quadrangular, 6–34(–40) × 2–3(–3.6) mm; floral scales deciduous, (8–)16–36(–42), spreading, laterally whitish, greenish, or pale brownish, medially green, weakly 7–9-ribbed, laterally weakly 1–2-ribbed, most ribs medial, ovate, (2.4–)2.6–3 × (1.9–)2–2.4(–2.5) mm, apex acute to ± acute, cuspidate tip (0.3–)0.5–0.7(–0.8) mm. Flowers: anthers 0.6–0.7 mm; styles 0.9–1.3 mm; stigmas 0.5–0.8 mm. Achenes brown, stipitate to sessile, obovoid, (1–)1.2–1.4(–1.5) × 0.9–1(–1.1) mm, apex obtuse to emarginate, surfaces very finely puncticulate.

Fruiting summer–early fall. Various disturbed soils; 0–900 m; Ala., Ark., Del., Fla., Ga., Ill., La., Md., Miss., Mo., N.Y., N.C., Ohio, Pa., S.C., Tex., Va.; Mexico; Central America; South America; Asia; Africa.