Southern Flat Sedge

Herbs, perennial, rhizomatous. Culms trigonous, (15–) 20–40(–65) cm × 0.5–1 mm, glabrous. Leaves V-shaped, (10–)20–40 cm × 0.8–2.8(–3) mm, glabrous. Inflorescences: spike 1, densely oblong-cylindric, (15–)25–35(–40) × 12–18(–22) mm, (spikelets loosely spaced, 7–9 per 5 mm of rachis); rays (5–)6–8(–11), 0.5–4(–7.5) cm; bracts (4–)5–7(–8), ascending at 30º, (4–)10–30(–35) cm × (1–)2–4(–7) mm; rachilla deciduous, wings persistent, 0.4–0.5 mm wide. Spikelets (20–)40–80(–100), linear, ± cylindric, scarcely compressed, (4.5–)6–9(–11) × (0.5–) 0.6–0.7(–1) mm; floral scales persistent, (1–)2–3(–4), appressed, medially green, laterally light brown to tawny or bronze, medially (1–)3-ribbed, laterally 3-ribbed, oblong, (2.6–)2.8–3.2(–3.4) × (1–)1.2(–1.4) mm, apex acute, mucronulate, mucro to 0.1(–0.2) mm. Flowers: anthers 0.6–0.8 mm; styles (0.4–)0.6–1(–1.2) mm; stigmas persistent on achenes, prominently exserted from floral scales, (1.5–)2–3(–4) mm. Achenes brown to reddish brown, stipitate, narrowly oblong, 1.8–2.1 × (0.4–)0.5(–0.7) mm, stipe 0.1–0.2 × 0.1–0.2 mm, apex apiculate, acute, surfaces puncticulate.

Ala., Fla., Ga., La., Tex.; Mexico; West Indies; South America.

Fruiting summer.

Dry, open woods; 0–200m.

Cyperus anceps Liebmann; C. dissitiflorus Nees ex Torrey; C. pallens (Liebmann) Standley & Steyermark; C. regiomontanus Britton var. pallens (Liebmann) Kükenthal; C. tribrachiatus (Liebmann) Kükenthal; Mariscus dissitiflorus (Torrey) C. B. Clarke; M. pallens Liebmann; M. tribrachiatus Liebmann

Cyperus thyrsiflorus is a species of sedge that is native to southern parts of North America, Central America and northern parts of South America.