Tradescant’s Aster, Shore Aster, aster de Tradescant
Symphyotrichum tradescantii (L.) Nesom occurs scattered along damp, rocky and gravelly shores, silt- or loam-filled cracks in rocky rapids of streams or along freshwater estuaries in Newfoundland, Québec, and New Brunswick in Canada and from Maine to New York and northern New Jersey in the US (Brouillet et al. 2006; ). Rays are white; disc florets are pale yellow turning purplish with age, corolla lobes are shorter than in Sy. lateriflorum. Colonial dams on rivers likely eliminated many populations in the southern portion of the range long ago.
Semple et al. (2024) summarized the published chromosome counts for S. tradescanti and presented the cytogeography of all counts. Diploids (2n=16) are more common than tetraploids (2n=32) and all counts come from more northern populations.
Brouillet, L., J.C. Semple, G.A. Allen,Ìý K. Chambers and S. Sundburg. 2006.  Symphyotrichum Nees. pp. 465-539. In Flora North America Editorial Committee, eds. Flora of North America. Vol. 20. Asteraceae, Part 2. Astereae and Senecioneae. Oxford University Press, New York.
Semple, J.C., J.G. Chmielewski, A. Bouchard, and L. Brouillet. 2024. The cytogeography Symphyotrichum lateriflorum,ÌýS. ontarionis,Ìý S. racemosum, and S. tradescantii (Asteraceae: Astereae). Phytoneuron 2024-68: 1–20.
Last revised 15 May 2025 by J.C. Semple
© 2025 J.C. Semple, including all photographs unless otherwise indicated
1-4. Symphyotrichum tradescanti. 1. Plant on gravel near pond, Semple & Keir 4900, Charlotte Co. New Brunswick. 2. Dwarf plant on rocks along south shore of St. Lawrence R., Semple & Brouillet 3395, Québec. 3. Small plant on rocks of R. St. Francois, Semple & Brouillet 3406, Québec. 4. Stem and leaves, Semple & Keir 4860, Nova Scotia, cult. greenhouse, U. À¶Ý®ÊÓÆµ.