Symphyotrichum cordifolium

Symphyotrichum cordifolium reaches heights of up to 1.2 meters (4 feet). The lower leaves are heart-shaped, while leaves higher on the stem tend to be sessile with more rounded bases. The composite flowers, which have bluish to rarely white ray florets and light yellow disc florets that eventually turn purple, emerge in August and persist into October.[3]

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  Symphyotrichum cordifolium leaves
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  Flower heads showing involucres
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  Close-up of an involucre showing phyllaries
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  Abaxial side of a leaf
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  Flower heads
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  Showing light blue rays

Symphyotrichum cordifolium is classified in the subgenus Symphyotrichum, section Symphyotrichum.[5] The species was first formally described by Carl Linnaeus in 1753 as Aster cordifolius.[6]

S. cordifolium botanical illustration from Addisonia, New York Botanical Garden (1917).

Symphyotrichum cordifolium occurs from Manitoba, east to Nova Scotia and Maine, south to Georgia and Alabama, and west to Oklahoma. It was once introduced in British Columbia but did not persist.[3] It is an introduced species in Great Britain and Norway.[2]

It grows primarily in mesic sites with soils that are rocky to loamy but generally rich, at heights ranging from sea level along the coastal plain up to 1,200 m (3,900 ft) in the Appalachian Mountains. It can be found on open wooded slopes, along the banks of streams, on moist ledges, in swampy woods, along the borders of beech–maple forests and oak–hickory forests, as well as in clearings, thickets, and along roadsides and ditches. It also can be found in urban areas where it is sometimes considered a weed species.[3]

Symphyotrichum cordifolium has coefficients of conservatism (C-values) in the Floristic Quality Assessment (FQA) that range from 2 to 8 depending on evaluation region.[9] The lower the C-value, the higher tolerance the species has for disturbance and the lesser the likelihood that it is growing in a presettlement natural community.[10] In the Dakotas, for example, S. cordifolium has a C-value of 8, meaning its populations there are found in high-quality remnant natural areas with little environmental degradation but can tolerate some periodic disturbance.[11] In contrast, in the Laurentian plains and hills of Maine and New Brunswick, it has been given a C-value of 2, meaning its presence in locations of that ecoregion provides little confidence of a remnant habitat.[12]

As of July 2021, NatureServe listed Symphyotrichum cordifolium as Secure (G5) worldwide, Critically Imperiled (S1) in Kansas, and Vulnerable (S3) in Delaware and Missouri.[1]