Symphyotrichum ericoides

Heath aster is a perennial herbaceous plant with stems from 30 to 91 centimeters (1 to 3 feet) tall.[6] Its leaves are sessile (stalkless) and narrow, becoming smaller towards the top of the plant and tips of the branching stem. It has white (rarely pinkish), composite flowerheads with yellow centers that begin flowering in late summer and last through fall.[7][8] They are 8 to 10 millimeters (1⁄3 to 1⁄2 inch) across.[6][5]

It is commonly confused with Symphyotrichum pilosum, which co-occurs throughout most of its range.[7][9][2][10] S. pilosum has larger flowerheads with longer ray petals. The phyllaries on S. pilosum are spine-tipped, while those of S. ericoides are not, although the curled edges may make them appear to be.[7]

Heath aster has two varieties: Symphyotrichum ericoides var. ericoides, which spreads by underground rhizomes to form colonies, and S. ericoides var. pansum (S.F.Blake) G.L.Nesom, which is cespitose, remaining in a clump, and has corm-like caudices.[3][11]

F1 hybridization with Symphyotrichum novae-angliae can occur where the ranges of these two species overlap. The hybrid is called Symphyotrichum × amethystinum (amethyst aster)[12] and is intermediate between the parent species in most respects.[13]

• 
  S. × amethystinum, center, is a hybrid between S. novae-angliae, right, and S. ericoides, left.

Symphyotrichum ericoides grows from Canada across much of the United States into the Mexican states of Coahuila and Nuevo León.[7] The variety S. ericoides var. ericoides prefers open locations with sandy, gravelly, or disturbed soil.[3]

As of October 2022, NatureServe listed S. ericoides as Secure (G5) globally, last reviewed on 16 May 2016. On a US state and Canadian province and territory basis, it listed the species as Vulnerable (S3) in New Jersey, Pennsylvania, and Virginia; Imperiled (S2) in Mississippi; Critically Imperiled (S1) in Georgia and Kentucky; Apparently Secure (S4) in Iowa, Manitoba, Maryland, and Northwest Territories; and, Secure (S5) in Alberta, British Columbia, Montana, New York, Ontario, and Saskatchewan. It is reported as an Exotic in Québec. The remaining states, territories, and provinces have not been ranked.[1]

• Asteraea Lab - University of Waterloo
• Symphyotrichum ericoides at Ladybird Johnson Wildflower Center, wildflower.org