Cyperus vegetus Willdenow

Herbs, perennial, cespitose, rhizomatous. Culms trigonous to terete, (25–)40–60(–90) cm, glabrous. Leaves flat or V-shaped, (10–)25–50 cm × 5–8(–12) mm. Inflorescences: heads globose, (10–)20–40 mm diam.; rays (0–)3–10, 2.5–5(–12) cm; 2d order rays usually absent (when present, 0.5–1.5 cm); bracts 4–8, horizontal to ascending at 15–30°, flat (or V-shaped), 3–30(–50) cm × 1.5–8(–12) mm. Spikelets (20–)30–50(–70), oblong, compressed, 5–20 × 2.2–3 mm; floral scales (12–)20–30(–50), off-white to golden brown, basally 2-keeled, laterally ribless, ovate-deltate, 2–2.3 × 1–1.4 mm (declined 30–40º from rachilla). Flowers: stamen 1; anthers 1–1.2 mm; styles 1–1.2 mm; stigmas 0.5 mm. Achenes black or dark brown, stipitate, broadly ellipsoid, 1.2–1.4 × 0.5–0.6 mm, stipe to 0.1 mm, apex apiculate, beak 0.2–0.3 mm, surfaces puncticulate.

Fruiting summer. Damp grasslands, roadsides ditches; 0–200 m; B.C.; Ala., Calif., La., Miss., N.J., Oreg., Pa., S.C., Tex., Wash.; South America; naturalized, Europe.

The distributions of Cyperus eragrostis in British Columbia, Alabama, Pennsylvania, South Carolina, and Texas represent introduced populations.