Cyperus thyrsiflorus

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.

Fruiting summer. Dry, open woods; 0-200 m; Ala., Fla., Ga., La., Tex.; Mexico; West Indies; South America.