Plants perennial, mostly densely cespitose, 20-70 cm, base deep rich red brown; rhizomes absent. Culms erect to ascending, leafy, stiff. Leaves shorter than scape; blades narrowly linear, (1-)2-3 mm wide, margins involute, apex trigonous, tapering. Inflorescences: clusters 1-2, if 2 then close together, dense, broadly turbinate to hemispheric or lobed globose; primary leafy bract linear, stiff, exceeding clusters. Spikelets light to dark red brown, lance ovoid, 3.5-6 mm, apex acuminate; fertile scales ovate, convex, 3-3.5(-4) mm, apex acuminate, low midrib excurrent or not. Flowers: perianth bristles 6, reaching at least to tubercle base, plumose from base to more than 1/2 length of fruit body. Fruits 1(-2) per spikelet, (2-)2.5-2.8(-3) mm; body red brown or brown, tumidly obovoid, (1.5-)2-2.2 × 1-1.7 mm; surfaces interruptedly transversely rugulose; tubercle broadly conic, 0.5-0.8(-1) mm, base broadly 2 lobed, apex often apiculate.

Fruiting spring-fall or all year. Sands and sandy peat of bog margins, pinelands and pine saw palmetto flats among wiregrass; 0-200 m; Fla.; West Indies (Cuba).

Rhynchospora pineticola is distinguished from taller extremes of R. plumosa by its thicker leaves and scapes and its longer spikelets and fruit. Its bases are a deep rich red-brown rather than the pale brown or dull deep brown of R. plumosa.