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Symphyotrichum ontarionis (Wiegand) G. L. Nesom is native to often shaded, usually moist, alluvial soils, alluvial streams or lake shores, floodplain deciduous forests or thickets, bogs, marshes, edges of fields, and roadsides in western Québec to Minnesota south to Alabama and eastern Texas (Brouillet et al. 2006; ). The species has been treated as Aster ontarionisÌý°Â¾±±ð²µ.,ÌýAster missouriensis Britt., and Aster pantotrichus Blake.ÌýÌýSymphyotrichum ontarionis is often confused with Sy. lateriflorum, from which it can be distinguished by its shorter disc corolla lobes that are yellow (never violet with age) and abaxial leaf surfaces that are either moderately to densely hairy or glabrous to glabrate (var. glabratum) without hairs along midveins (as is typical of Sy. lateriflorum).  The species includes diploids 2n=16 (var. glabratum) and tetraploids 2n=32 (var. ontarionis). Semple et al. (2024) reviewed all published counts and presented a cytogeography map for the two varieties. 

Two varieties are recognized.

Abaxial leaf faces moderately to densely hairy       var. ontarionis
Abaxial leaf faces glabrous or glabrate                   var. glabratum

Last revised 15 May 2025 by J.C. Semple

© 2025 J.C. Semple, including all photographs unless otherwise indicated