Plants 40-200 cm ; rhizomes creeping, thick. Stems 1-10+, erect, proximally glabrous, glabrous or sparsely villoso-strigose in arrays; often with short fascicles in axils of mid to distal cauline leaves. Leaves: rosettes present at flowering; basal and proximal tapering to winged petioles, blades oblanceolate, 70-210 × 8-28 mm, somewhat fleshy (fresh), margins entire, sometimes shallowly crenate or serrate distally, sometimes undulate, apices acute, mucronate or attenuate, glabrous; mid and distal cauline not crowded, sessile, blades lanceolate to linear-lanceolate, 10-120 × 5-16 mm, reduced distally, margins entire. Heads 60-100 , in thyrsiform-paniculiform arrays, sometimes secund apically, (3.5-)6-26(-60) x 4-10(-15) cm, branches ascending to arching. Peduncles 2-8 mm, glabrous or sparsely strigose; bracteoles 0-4. Involucres narrowly campanulate, 3-4 mm. Phyllaries in 3-4 series, outer narrowly ovate to lanceolate (1.5-3 × 0.4-1 mm), unequal, obtuse to acuminate. Ray florets (5-)11-15; laminae 1.5-3.5 × 0.5-0.75 mm. Disc florets 8-22; corollas 2.5-4.5 mm, lobes 1-1.5 mm. Cypselae (narrowly obconic) 1.5-2.5 mm (ribs 5-8, broad, lighter than body), sparsely strigose; pappi 3-4 mm. 2n = 18.

Flowering Jul-Oct. Bogs, seepage areas at higher elevations, streamsides in desert at proximal elevations, tolerant of alkaline meadows and hot springs; 300-2600 m; Ariz., Calif., Idaho, Nev., Oreg., Utah.