Cyperus elatus Rottbøll, Descr. Icon. Rar. Pl., 37, plate 10. 1773, not Linnaeus 1756

Herbs, perennial, rhizomatous. Culms single or close together, trigonous, (10–)40–80(–120) cm × 1.2–2.5(–5) mm, glabrous. Leaves 2–5, pleated, (10–)20–50(–90) cm × 2–5(–10) mm. Inflorescences: spikes 1–4(–7), loose, broadly ovoid to ovoid-pyramidal, 25–35 × 25–35 mm; rays (4–)5–6(–8), (1–)3–8(–16) cm, glabrous; 2d order rays (0–)1–5, 5–15(–50) mm; bracts 4–7, ascending at 30–45°, pleated, (5–)20–40(–60) × (2–)3–8(–11) mm; 2d order bracts 1–4 per ray, 5–10(–30) × 0.5–1 mm, scabridulous; rachilla persistent, wingless (or very narrowly winged, not clasping achene). Spikelets (10–)20–35(–45), seemingly flattened proximally from spreading floral scales, becoming terete apically, linear, (10–)13–18(–25) × 1.2–1.5(–1.6) mm; floral scales deciduous, (10–)12–20(–25), laterally light reddish brown to dark red, medially greenish, laterally ribless, medially 3–5-ribbed, oblong-ovate, 1.7–2(–2.4) × 0.9–1.2 mm, apex obtuse, barely reaching next scale, apex entire, emarginate, mucro at most 0.3 mm. Flowers: anthers 0.4–0.5 mm; styles 0.3–0.6 mm; stigmas 1–1.8(–2) mm. Achenes dark brown, narrowly oblong, (1.3–)1.4–1.6(–1.7) × (0.3–)0.4–0.5 mm, base cuneate to ± stipelike, apex acute, not apiculate, surfaces papillose.

Fruiting summer. Marshes; 0 m; Fla., N.C.; Mexico; West Indies (Dominican Republic south through the Lesser Antilles); South America; Asia; Africa.