Perennials 20-60 cm, colonial; long-rhizomatous. Stems 1-5+, ascending to erect, densely and uniformly strigose, especially distally. Leaves (grayish green) thin to firm, margins entire, apices acute, faces glabrous or strigose; basal usually persistent, petiolate, blades oblanceolate, 50-150 × 5-12(-15) mm, bases attenuate or cuneate, margins entire, apices usually acute; proximal cauline sessile or subpetiolate, blades oblong to narrowly obovate, 50-120 × 5-12 mm, bases attenuate or cuneate; distal sessile, blades 30-70 × 4-10 mm, reduced distally, bases cuneate to ± rounded. Heads in paniculiform arrays, branches ascending. Peduncles moderately to densely strigose, bracts 1-4, linear to oblanceolate. Involucres campanulate, 4-7 mm. Phyllaries in 3-5 series, narrowly oblanceolate or linear (outer) to linear (inner), unequal, bases indurate, margins entire, green zones obovate to elliptic, apices obtuse, faces densely strigose. Ray florets (10-)15-40; corollas violet, laminae 8-13 × 1-1.5 mm. Disc florets 25-65(-80); corollas yellow, sometimes purple-tinged, 4-6 mm, lobes triangular, 0.4-0.8 mm. Cypselae brown, cylindric to obovoid, not compressed, 2-3.5 mm, 3-5-nerved, faces hairy; pappi whitish, 4-7 mm. 2n = 26, 36, 52. Flowering Jul-Aug. Meadows, grasslands, damp areas in sagebrush steppe and Ponderosa pine woodlands; 500-3200 m; Alta., B.C., Sask.; Ariz., Calif., Colo., Idaho, Mont., Nev., N.Mex., N.Dak., Oreg., Utah, Wash., Wyo. Symphyotrichum ascendens is widely distributed in the Great Basin. It is an allopolyploid derived from the hybrid between S. spathulatum (x = 8) and S. falcatum (x = 5). Chromosome numbers differ markedly in their geographic distribution, 2n = 26 prevailing in the southwestern part of the range, and 2n = 52 in the northeastern part (G. A. Allen 1985) Backcrosses to both parental species or hybrids with related taxa are sometimes seen where the ranges overlap.