Plants perennial, densely cespitose, 6-75 cm; rhizomes mostly absent. Culms erect to curved, leafy, obscurely trigonous to nearly terete, few ribbed, slender. Principal leaves mostly overtopped by culm; blades narrowly linear to filiform, proximally flat, 0.5-1.5 mm, apex tapering, trigonous. Inflorescences: clusters 1 or 2-3, then widely spaced, narrowly turbinate to hemispheric, 1.5-2.5 cm wide; subtending leafy bracts often exceeded by distal cluster. Spikelets pale brown to nearly white, ellipsoid, 3.5-5.5 mm, apex acute; fertile scales elliptic, 3-3.5(-4) mm, apex acute or acuminate, midrib excurrent as mucro. Flowers: perianth bristles 10-12, slightly overtopping tubercle, retrorsely barbellate or rarely smooth, base often setose. Fruits 1(-2) per spikelet, (2.3-)2.5-3 mm; body pale brown with paler center, stipitate obovoid, lenticular, 1.5-1.8(-2) × 0.9-1.2 mm; surfaces transversely striate, relatively smooth, rim narrow, flowing to tubercle base; tubercle narrowly triangular subulate, 0.5-1.2 mm. Fruiting summer-fall. Acid, sphagnous, boggy, open sites, poor fens, often on floating mats or peaty interstices of rocky shores; 0-2000 m; Alta., B.C., Man., N.B., Nfld. and Labr. (Nfld.), N.W.T., N.S., Ont., P.E.I., Que., Sask.; Alaska, Calif., Conn., Del., Fla.(-), Ga., Idaho, Ill., Ind., Maine, Md., Mass., Mich., Minn., N.H., N.J., N.Y., N.C., Ohio, Oreg., Pa., R.I., S.C., Tenn., Vt., Va., Wash., W.Va., Wis.; West Indies (Puerto Rico); South America(-); Eurasia. The smooth-bristled Rhynchospora alba forma laeviseta Gale mostly occurs with the typical antrorsely barbellate type in Pennsylvania, the Great Lakes, British Columbia, Newfoundland, and Nova Scotia.
Erect perennial to 7 dm, the clustered, very slender stems usually overtopping the lvs, these 0.5-2.5 mm wide; glomerules 1-3, broadly turbinate, 6-20 mm thick, the uppermost barely or scarcely surpassed by its bracts, the lateral ones usually remote and long-pedunculate; spikelets 4-5 mm, whitish, becoming pale brown, with 2(3) fls and 1 or 2 frs; bristles 8-14, biseriate, stout, flattened, about equaling the tubercle, usually retrorsely barbellate, often minutely antrorse-hairy at base; achenes flattened-pyriform, 1.5-2 mm, contracted at base, brownish-green with very faintly transverse brown lines; tubercle subulate, half to two-thirds as long as the achene; 2n=26, 42. Sphagnum- bogs and open conifer-swamps; circumboreal, s. to N.C., O., n. Ind., Minn., and Calif.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.