Perennials, (20-)30-70 cm, cespitose, eglandular; with short, woody, cormoid caudices, or short rhizomes. Stems 1-5+, ascending to erect (thin, grayish brown to dark brown), glabrous proximally, densely canescent distally. Leaves (silvery) firm, soft; basal withering by flowering, sessile, blades (1-3 nerved) elliptic-lanceolate, 10-40 × 5-15 mm, bases cuneate, weakly sheathing, margins usually entire, rarely remotely serrate, piloso-ciliate, apices acute, faces less copiously hairy than cauline; proximal cauline withering by flowering, sessile, blades oblanceolate or oblong to linear-lanceolate, 15-30(-50) × 4-10 mm, slightly and progressively reduced distally, bases rounded, sub­clasping, margins entire, silky-pilose, apices obtuse to acute, mucronulate, faces sparsely to densely silky-pilose; distal sessile, blades lanceolate, 10-30 × 5-8 mm, little reduced distally, bases cuneate, margins entire, apices acute, mucronate, faces ± densely silky. Heads in open, paniculiform arrays, branches sparse, fastigiate, often arching (1-5+ per branch). Peduncles subsessile or 0.5-3(-5) cm, densely sericeo-strigose, bracts crowded, 4-8(-10) mm, grading into phyllaries. Involucres campanulate to cylindric, (5-)7.5-10 mm. Phyllaries in 3-5(-6) series, outer ovate with expanded distal portion [(4-)5-6 mm], mid ovate-lanceolate [6-8(-10) mm] with expanded green portions, inner linear, unequal or sometimes subequal, outer often foliaceous, bases (mid) scarious, margins silky, green zones restricted to expanded distal ¹ / 2 - ² / 3 (obscured by hairs), apices (outer) spreading or squarrose to reflexed, acute, mucronulate, faces densely long-silky. Ray florets (10-)15-30; corollas usually rose-purple to deep purple, rarely white, laminae 8.5-11 × 1-1.5 mm. Disc florets (15-)25-35; corollas pink turning purple, (5-)5.5-7 mm, tubes shorter than narrowly funnelform throats (both thinly puberulent), lobes deltate, 0.7-0.9 mm. Cypselae purple or brown, obovoid, not compressed, 2-3 mm, 7-10-nerved (prominent), faces glabrous; pappi whitish or tawny, 6-7 mm. 2n = 10, 20. Flowering Aug-Oct. Open, dry, deep, sandy or loamy soils, broken limestone outcrops, open-wooded bluffs, open woods, open calcareous hammocks, prairies, fields, sand barrens, dunes, dry banks, rarely acidic shield rocks; 100-500+ m; Man., Ont.; Ark., Ga., Ill, Ind., Iowa, Kans., Mich., Minn., Mo., Nebr., N.Dak., Ohio, Okla., S.Dak., Tenn., Tex., Wis.; West Indies (Bahamas). Symphyotrichum sericeum is known in the Bahamas as S. lucayanum (Britton) G. L. Nesom [syn. Aster lucayanus Britton, Virgulus lucayanus (Britton) Reveal & Keener]. It is of conservation concern in Indiana, Michigan, and Canada. Symphyotrichum sericeum is distinct and unlikely to be confused with other species due to its silvery-silky leaves and phyllaries, open arrays, and cormoid rootstocks. Aster sericeus forma albiligulatus Fassett is a white form of the species, in contrast to the typically purple forma sericeus; these do not deserve formal recognition.