Perennials, 30-90(-100) cm, colonial or cespitose; long-rhizomatous or with woody caudices. Stems 1-3+, erect (straight), glabrous or glabrate. Leaves thin, margins often ± revolute, scabrous, apices mucronate to mucronulate, faces glabrous or abaxial minutely pilosulous, cauline with clusters of smaller leaves in most axils; basal withering by flowering (new vernal rosettes often present), petiolate (petioles narrowly winged, sheathing, strigoso-ciliate), blades spatulate to oblanceolate, 5-40 × 5-15 mm, bases attenuate or cuneate to rounded, margins crenate-serrate, apices obtuse to acuminate; proximal cauline withering by flowering, petiolate or subpetiolate (proximalmost) or sessile (petioles winged, sparsely long strigoso-ciliate), blades elliptic or elliptic-lanceolate to lanceolate or linear-lanceolate, 20-70 × 3-20 mm, progressively reduced distally, bases clasping, margins becoming short-ciliate distally; distal (ascending or spreading) usually sessile, sometimes subpetiolate, blades linear-lanceolate to linear, 5-60+ × 1-8 mm, notably unequal in size, reduced distally, abruptly so on branches, bases cuneate to attenuate, margins serrulate or entire. Heads in diffuse, ± pyramidal, paniculiform arrays, branches ± lax, spreading horizontally or arching, racemiform, subtended by patent to reflexed branch leaves, often crowded but not (or barely) secund. Peduncles slender, 0.2-3+ cm or subsessile, hairy in lines, bracts 5-15, linear-elliptic to acicular, 1-2 mm, glabrous, grading into phyllaries. Involucres cylindric, (2.5-)3.5-4.5(-5.5) mm. Phyllaries in 4-6 series, appressed or outer ± spreading, oblong-lanceolate to linear (innermost) , unequal, bases indurate 1 / 4 - 1 / 2 , margins narrowly scarious, hyaline, ciliolate, green zones oblanceolate to linear-oblanceolate, apices acute to acuminate, mucronate, sometimes lightly purple-tinged, faces glabrous. Ray florets (12-)16-20; corollas usually white, rarely pink, laminae 5-8 × 0.5-1.2 mm. Disc florets 10-20(-25); corollas cream or pale yellow becoming pink or red, (2.5-)3-4.5 mm, tubes shorter than narrowly funnelform throats, lobes recurved to erect, lanceolate, 0.5-1 mm. Cypselae gray to tan, obovoid, ± compressed, 1-1.8 mm, 4-5-nerved (faint), faces sparsely strigillose or sericeus; pappi white, 2.5-3.5 mm. 2n = 16. Flowering Aug-Oct. Moist to wet, often alluvial soils, often brackish, marshes, savannas, bogs, wet meadows, prairie swales, swamps, borders of swamps, open bottomwoods; 0-200 m; N.B., Ont.; Ala., Ark., Conn., Del., D.C., Fla., Ga., Ill., Ind., Iowa, Ky., La., Maine, Md., Mass., Mo., N.J., N.Y., N.C., Ohio, Okla., Pa., R.I., S.C., Tenn., Tex., Vt., Va., W.Va. Symphyotrichum racemosum is introduced in Canada. The species is cultivated commercially under the name Aster ericoides cv. `Spray´. A. G. Jones (1989) reported hybridization with S. dumosum, S. lateriflorum, S. lanceolatum var. interior, and S. ontarionis. The name Aster vimineus Lamarck has been misapplied to this taxon.
