Plants perennial, densely cespitose, 15-60 cm; rhizomes compact, branching, slender. Culms lax, filiform, leafy, terete, grooved. Leaves ascending to erect, exceeded by culm; blades lax, filiform, margins proximally deeply involute, apex trigonous, tapering. Inflorescences mostly cymose clusters, simple or compound, 1-3(-4), widely spaced, loose, narrowly to broadly turbinate; branchies capillary, ascending to spreading; leafy bracts setaceous, exceeded by or exceeding cymes. Spikelets light red brown or brown, lance ovoid to fusiform, 3-4(-4.5) mm, apex acuminate; fertile scales ovate, mostly 2-3 mm, apex rounded to acute, midrib included or short excurrent. Flowers: perianth bristles mostly 6, unequal, rarely extending past fruit midbody, an-trorsely barbellate. Fruits 1-4 per spikelet, 1.8-2 mm; body yellow brown to brown, lustrous, tumidly obovoid lenticular, 1-1.5 × 1-1.5 mm; surfaces transversely wavy rugose, intervals vertically striate with narrow alveolae; tubercle flat, triangular, 0.3-0.6 mm. Fruiting spring-summer or all year (south). Sands or peats of low savannas, seeps, bogs, flatwoods, pond shores, stream banks; 0-400 m; Ala., Ark., Fla., Ga., La., Md., Miss., N.J., N.C., Okla., S.C., Tenn., Tex., Va.; Mexico; West Indies; Central America. Rhynchospora rariflora forms solid tussocks by means of short, forking, compact masses of rhizomes.