Symphyotrichum cordifolium is a perennial herb 20-120 cm. tall from a short rhizome; stem usually hairless below inflorescence.
Leaves alternate heart-shaped, deeply, sharply toothed, to 15 cm long, 7 cm wide, rough above esp. near margins, sometimes hairy below, tip long-pointed, base deeply lobed, stalks usually not winged.
Flowers in small, daisy-like heads, rays blue-white to pale blue, 8-20, 0.5-1 cm long, disk flowers yellow, becoming dark purplish, bracteate base of flower head 0.3-0.6 cm, bracts narrow, overlapping, appressed, green with dark tips (see Asteraceae); inflorescence branched, pyramidal, many-flowered, with small leafy bracts on flower stalks; blooming and fruiting, Sept.-Oct.; insect pollinated.
Fruit dry, 1-seeded, achene, with tuft of hairs (pappus), wind dispersed.
Wetland status: UPL.
Frequency in NYC: Occasional.
Habitat: Upland woodlands, partial shade, edges, drought and shade tolerant.
Notes: Similar to white wood aster but A. cordifolius blooms later and has smaller, more numerous flowers that are blue or bluish-white, on a larger inflorescence than those of A. divaricatus. Leaves of both species virtually identical early in season.