Perennial greenhead sedge

Cyperus brevifolius (Rottbøll) Endlicher ex Hasskarl

Plants perennial, cespitose or not, long-creeping rhizomatous. Culms sometimes spaced to 3 cm apart, (5–)12–25(–55) cm, smooth. Leaves flat, 2–21 cm × 1.5–3.5 mm. Inflorescences: spikes 1–3, 4–7 × 4 mm; bracts 3–4, longest ± erect, others ascending to horizontal, flat, 1.5–18 cm × 1–3.3 mm. Spikelets (20–)40–60(–100), pale greenish or reddish brown, ovate, (2.2–)2.5–2.8(–3.2) × (0.6–)0.7–0.8(–1.2) mm; floral scales laterally 2–3-veined, elliptic to ovate, 1.8–3 × (0.8–)1.1–1.6 mm, midvein not winged, apex mucronate; stamens (1–)2; anthers 0.8–1.1 mm; style 0.6–1.2 mm; stigmas 0.5–1.5 mm. Achenes brown, substipitate or stipitate, ellipsoid to oblong-ellipsoid, 1–1.2(–1.3) × 0.6–0.8 mm, stipe, if present, 0.1–0.2 mm, apex obtuse to subtruncate, apiculate, papillate.

Fruiting summer. Damp grasslands, shorelines, ditches, croplands; 0–200 m; Ala., Calif., Fla., Ga., La., Miss., N.C., Okla., S.C., Tex.; Mexico; West Indies; Central America; South America; Asia; Africa; Australia.

Reports of Kyllinga brevifolia from Connecticut, Delaware, Maryland, New Jersey, Pennsylvania, and Virginia should be referred to as K. gracillima.