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.
Cespitose, 2-5 dm, the stems and lvs filiform; cymes 1-3, small and loosely branched, each of the 3-6 spikelets on an elongate, capillary pedicel; spikelets ovoid,
3-4 mm, castaneous, 2-4-fld, with 1-3 frs; bristles 6, antrorsely barbellate, unequal, the longest to 0.5 mm; achenes brown, plump, broadly obovoid or subrotund, 1.2-1.5 mm, transversely ridged; tubercle flat, deltoid, 0.3-0.5 mm. Bogs and wet soil on the coastal plain; N.J. to Fla., Tex., and trop. Amer.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.