Plants annual, cespitose or solitary, (10–)20–100 cm; rhizomes absent. Culms erect, leafy, nearly terete or angled, manyribbed. Principal midculm leaves often exceeding inflorescences; blades linear, proximally flattened, 1–5 mm wide, apex trigonous, tapering. Inflorescences terminal and axillary, clusters of corymbs 1–5, usually diffuse; leafy bracts exceeding proximal corymbs. Spikelets dark brown, lanceoloid to ovoid, mostly 4–6(–8) mm, apex acute; fertile scales many, ovate, rounded-convex, 2–3.5 mm, apex acute, midrib mostly included, rarely forming apiculus. Flowers: perianth absent. Fruits 1–1.3(–1.5) mm, body dark brown, tumidly lenticular, nearly orbicular, 0.7–1 × 0.7–1 mm, margins strong, interrupted at tubercle base; surfaces irregularly transversely rugulose with wavy rows of vertical, linear, raised cells; tubercle depressed-triangular, 0.1–0.3 mm, capping fruit summit, base broadly 2lobed.
Phenology: Fruiting summer–fall or all year.
Habitat: Moist to wet sands or peats of stream banks, pond shores, depressions in savannas, marshes
Elevation: 0–100 m
Ala., Del., Fla., Ga., Ind., La., Mass., Mich., Miss., N.J., N.Y., N.C., S.C., Tex., Va., West Indies, Central America.