Plants perennial, cespitose, 80-150 cm; rhizomes absent. Culms erect with arching tops, leafy, obscurely trigonous, slender. Leaves overtopped by inflorescence; blades linear, proximally flat, 3-5 mm wide, apex trigonous, subulate, tapering. Inflorescences: spikelet clusters mostly 4-6, various in shape and crowding, narrowly to broadly turbinate; peduncles erect, branches slender, ascending; leafy bracts exceeding all but most distal clusters. Spikelets red brown, broadly ellipsoid, (1.5-)2-3(-3.5) mm, apex acute; fertile scales broadly ovate, 2-3 mm, midrib excurrent as apiculus or awn. Flowers: perianth bristles 6, mostly spreading, usually exceeding tubercle, antrorsely barbellate. Fruits 2-3(-4) per spikelet, 1.5(-1.7) mm; body pale brown to brown, strongly flattened, obovoid orbicular, 1-1.2 × 0.8-1.1; surfaces transversely wavy rugose, intervals vertically striate with very narrowly rectangular alveolae; tubercle flat, triangular or concavely triangular, 0.3-0.5(-0.7) mm.

Fruiting late spring-fall or all year (south). Sands and peats of bogs, shorelines, interdunal swales, savannas, and pine flatwoods; 0-200 m; Ala., Fla., Ga., La., Miss., N.C., S.C., Tex.

Rhynchospora elliottii is most likely to be confused in the field with its frequent associates R. microcarpa and R. perplexa. Most of the time it can be distinguished from both by its taller, coarser, broader-leaved habit and by its distinctly redder spikelets. Inspection of the fruit reveals the spreading character of the perianth bristles, these usually a length level with the tubercle tip or longer and giving the whole structure the appearance of an unengorged tick.