Proc. Amer. Acad. Arts. 17: 193. 1882.
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.
Phenology: Flowering Jul–Oct.
Habitat: Bogs, seepage areas at higher elevations, streamsides in desert at proximal elevations, tolerant of alkaline meadows and hot springs
Elevation: 300–2600 m
Ariz., Calif., Idaho, Nev., Oreg., Utah.
"thick" is not a number.