Western mountain aster

Aster spathulatus Lindley in W. J. Hooker, Fl. Bor.-Amer. 2: 8. 1834

Perennials, 20–80 cm, colonial; long-rhizomatous. Stems 1–5+, ascending to erect, glabrous or sparsely puberulent. Leaves thin, margins entire, apices acute, faces glabrous or sparsely puberulent; basal persistent, petiolate, blades narrowly elliptic to obovate, 50–150 × 3–15 mm, attenuate, margins entire; proximal cauline sessile or subpetiolate, blades linear to narrowly elliptic, 50–150 × 2–15 mm, bases attenuate or cuneate; distal sessile, blades 30–60 × 2–10 mm, reduced distally, bases cuneate to rounded. Heads in corymbiform to paniculiform arrays, branches usually few. Peduncles sparsely hairy, bracts 0–3+. Involucres campanulate, 5–10 mm. Phyllaries in 3–5 series, narrowly oblong or linear (outer) to linear (inner), unequal, bases indurate, margins entire, green zones elliptic to lanceolate , apices usually acute, sometimes obtuse, faces glabrous or ± puberulent. Ray florets 15–40; corollas violet, laminae 9–15 × 1–2 mm. Disc florets 30-80(–100); corollas yellow, sometimes becoming reddish, 4.5–6 mm, lobes triangular, 0.5–1 mm. Cypselae brown, cylindric to obovoid, not compressed, 2.5–3.5 mm, ± 4-nerved, faces hairy; pappi whitish, 5–7 mm.

Varieties 3 (3 in the flora): w North America, nw Mexico.

Symphyotrichum spathulatum is a variable species, widespread in montane regions of western North America. It hybridizes with S. eatonii, S. foliaceum, and S. hendersonii.