Herbs, perennial, cespitose, rhizomatous. Culms trigonous, (1-) 20-40(-75) cm × 1-1.5(-2.5) mm, glabrous. Leaves inversely W-shaped, 10-40(-70) cm × (1-)3-6(-10) mm. Inflorescences: spikes 1(-3), broadly and loosely ovoid to oblong-ellipsoid, (15-)20-30(-50) × 20-30(-45) mm; bracts (3-)5-7(-10), ascending at 30(-45)°, inversely W-shaped, 10-30(-50) cm × (1-)3-5(-11) mm; rays (2-)3-6(-12), (1-)3-10(-17) cm; rachilla deciduous, wings ca. 0.3 mm wide. Spikelets (10-)25-50(-100), ± terete, (appearing compressed due to excurved apices of floral scales), (8-)12-15(-24) × (0.8-)1.1-1.4(-1.8) mm; floral scales persistent, (4-)6-8(-14), golden brown, off-white to stramineous, densely red-glandular punctate, green medially, 3-4-ribbed laterally, 3-5-ribbed medially, oblong-lanceolate, (3.2-)4-4.5 × 1.2-1.6 mm, apex blunt, mucronulate to mucronate, mucro 0.2-0.5 mm; proximal scales mucronulate, distal scales mucronate; terminal scale conduplicate. Flowers: anthers 0.5-0.8(-1.4) mm; styles 0.8-1 mm; stigmas 1-2 mm. Achenes brown, ± sessile to stipitate, oblong-ellipsoid, 1.7-2 × 0.6-0.7 mm, 0.1(-0.2) × 0.2 mm, apex rounded, apiculate from dark purple style base, surfaces papillose.

Fruiting spring-summer. Thickets, open woods; 0-50 m; Fla., Tex.; Mexico; West Indies.

Cyperus lentiginosus has been treated as a variety of C. tenuis (G. Kükenthal 1935-1936). The two taxa differ in the longer scales with cuspidate apices of C. lentiginosus, the inversely W-shaped leaves and bracts (those of C. tenuis are V-shaped), and the open spikes (those of C. tenuis are dense).