Symphyotrichoid Asters in the restricted sense
Symphyotrichum Nees in the narrow sense includes all the many x=8, 7, 6, 5 and 4 species of asters native to North America (Semple et al. 2002). Several species are naturalized in Europe (S. lanceolatum, S. novi-belgii). Neither of these has glandular phyllaries. Species are distinguished on the basis of differences in habit, leaf shape and bases, inflorescence branching pattern, involucre size and presence/absence of stalked glands, phyllary shape and chlorophyllous zone pattern, number of ray and disc florets, and fruit traits. Semple and Hood (2005) described the details of pappus variation in the genus. Brouillet et al. 2006 (FNA) covered 77 of the ca. 90 species in the genus.
Summary of the classification of Symphyotrichum s.s. and links to individual species
Semple, J.C. and J.L.A. Hood. 2005. Pappus variation in North American Asters. I. Double, triple and quadruple pappus in Symphyotrichum and related aster genera (Asteraceae: Astereae). Sida 21: 2141--2159.
Brouillet, L., J.C. Semple, G.A. Allen, 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.
Revised 5 May 2021 by J.C. Semple
© 2021 J.C. Semple, including all photographs unless otherwise indicated