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FNA | Family List | FNA Vol. 20 | Asteraceae | Symphyotrichum

76. Symphyotrichum ascendens (Lindley) G. L. Nesom, Phytologia. 77: 276. 1995.

Long-leaved or intermountain or western aster

Aster ascendens Lindley in W. J. Hooker, Fl. Bor.-Amer. 2: 8. 1834; A. chilensis Nees subsp. ascendens (Lindley) Cronquist

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.


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