Symphyotrichum lanceolatum (Willd.) G.L. Nesom
Panicled aster, Eastern lined aster, tall white aster, lance-leaf aster, narrow-leaf michaelmas daisy, white-panicle aster
Panicled aster is a widespread North American native.
Identification: Plants are 12-59" (30-150 cm) in height, rarely up to 6½' (2 m). They consist of a single main stem that branches in the flowering region. The stem may be hairy or hairless. Leaves are ⅜-3" (1-8 cm) × ⅛-¾" (5-20 mm), with serrated or scalloped edges, oblanceolate or lanceolate. Dead leaves tend to curl a lot. Flowerheads are panicles that may be heavily branched and densely or quite sparsely flowered. Flowers are white to pinkish or pale blue-violet, ⅜-¾" (1-2 cm) across, with 16-50 rays and usually 20-40 tiny disc florets. Central disks are yellow, aging to purple. Maybe it is a coincidence, but the petals (rays) seem less orderly than with many asters.
See our aster comparison table here. Or check Arieh Tel’s well-researched and informative aster comparison site.
Symphyotrichum lanceolatum on Ontario Wildflowers
Symphyotrichum lanceolatum on gobotany.nativeplanttrust.org
Symphyotrichum lanceolatum on the Connecticut Botanical Society's Connecticut wildflowers site
Symphyotrichum lanceolatum on eFloras
Clemants, Steven; Gracie, Carol, Wildflowers in the Field and Forest, Oxford University Press, 2006, p. 22
Symphyotrichum lanceolatum description by Thomas H. Kent, last updated 25 May 2020.