Symphyotrichum ontarionis

Ontario or Bottomland Aster, aster du lac Ontario

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; FNA). The species has been treated as Aster ontarionis Wieg., Aster missouriensis Britt., and Aster pantotrichus Blake.  Symphyotrichum 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.

• var. ontarionis
• var. glabratum