Perennials, 10–40 cm, colonial or cespitose; long-rhizomatous. Stems 1–5+, ascending to erect (light to dark brown), proximally glabrous, distally strigose, stipitate-glandular. Leaves (light green) firm, margins entire, scabrous; basal sometimes persistent, sessile, blades (1–3-nerved) linear-oblanceolate, 10–30 × 4–10 mm, bases attenuate, apices obtuse, mucronate, faces glabrate to sparsely scabrous; proximal cauline withering by flowering, sessile, blades (3-nerved) narrowly oblanceolate, 20–80 × 2–8 mm, bases cuneate, apices obtuse to acute, mucronulate or white-spinulose, faces glabrous or moderately short-strigose, stipitate-glandular; distal sessile, blades linear-oblanceolate to -lanceolate or oblong (distally), 20–50 × 2–5 mm, ± reduced distally, bases ± clasping to cuneate, apices acute, mucronulate, faces glabrous or moderately short-strigose, stipitate-glandular. Heads 1–10(–30), borne singly or in paniculiform arrays, branches ascending. Peduncles sparsely to moderately short-strigose, moderately stipitate-glandular, bracts ± ascending, linear to narrowly-lanceolate. Involucres campanulate to cylindro-campanulate, 5.5–8 mm. Phyllaries in 3–4 series, linear to lanceolate, subequal to unequal, bases ± indurate, margins scarious, green zones covering distal portion, apices acute to acuminate, outer ± foliaceous, spreading to reflexed, faces glabrate, sparsely to densely stipitate-glandular. Ray florets 15–31; corollas violet, laminae (5–)6–15 × 1–2 mm. Disc florets 25–40; corollas yellow, 4.5–6 mm, lobes triangular, 0.4–0.8 mm. Cypselae light brown, sometimes translucent reddish brown between ribs, narrowly obovoid, ± compressed, 2–2.5 mm, 3–4-nerved (faint), moderately strigose on ribs; pappi tawny, 3.8–6 mm. 2n = 10.
Phenology: Flowering Aug–Oct.
Habitat: Open, often dry, disturbed, rocky and sandy soils near ponds and streams, dry grass meadows, open pine-douglas fir forests, plains to montane zones
Elevation: 1500–2500 m
Alta., B.C., Calif., Colo., Idaho, Mont., Nev., Oreg., Wash., Wyo.
Two poorly defined varieties of Symphyotrichum campestre have been described. Variety campestre has glabrous or sparsely strigose leaves and occurs in southern British Columbia, Colorado, Idaho, Montana, Nevada, Oregon, Washington, and Wyoming. Bloomer’s Aster, var. bloomeri, has moderately strigose leaves and occurs in California, Nevada, and Oregon. The varieties are not sufficiently distinct to warrant recognition. Symphyotrichum ×columbianum (Piper) G. L. Nesom (syn. Aster columbianus Piper, A. multiflorus Aiton var. columbianus (Piper) S. F. Blake, Virgulus ×columbianus (Piper) Reveal & Keener) is the hybrid between S. campestre and S. ericoides subsp. pansum.