Perennials 40-100 cm, cespitose; short-rhizomatous. Stems 1-10+, ascending to erect, glabrous or sparsely puberulent. Leaves thin, margins entire or sometimes serrate, apices acute; basal withering by flowering, petiolate, blades narrowly lanceolate, 60-200 × 10-20 mm, attenuate or cuneate, margins usually entire, sometimes serrate, apices acute, faces glabrous or sparsely puberulent; proximalmost cauline sometimes withering by flowering, sessile, blades narrowly lanceolate, 50-150 × 8-25 mm, bases cuneate, often auriculate, apices acute; distal sessile, blades linear to narrowly lanceolate, 20-120 × 3-20 mm, bases cuneate, often auriculate , apices acute. Heads in racemiform to narrow, paniculiform arrays, branches usually to 10 cm. Peduncles sparsely hairy , bracts linear to lanceolate. Involucres campanulate, 5-8 mm. Phyllaries in 3-5 series, often spreading, oblanceolate (outer) to linear (inner), subequal, outer indurate less than 1 / 2 , bases outer variable, inner scarious, margins entire, scabrous to ciliolate, green zones oblanceolate to elliptic, apices acute to obtuse, often spreading, faces glabrous or sparsely puberulent. Ray florets 20-40; corollas white to pink, laminae 7-15 × 1-2 mm. Disc florets 35-60+; corollas yellow, 4.5-5 mm, lobes triangular, 0.5-0.75 mm. Cypselae brown, cylindric to obovoid, not compressed, 2.5-3.5 mm, 1-2-nerved, faces hairy; pappi white, 5-6 mm. 2n = 16, 32, 48, 64. Flowering Jul-Aug. Moist to wet sunny places, wet thickets, along streams and ditches; 500-3100 m; Alta., B.C., Sask.; Ariz., Calif., Colo., Idaho, Mont., Nev., N.Mex., Oreg., Utah, Wash., Wyo.