The Symphyotrichum Clade

SYMPHYOTRICHOID ASTERS IN THE BROAD SENSE

Subtribe Symphyotrichinae Nesom sensu Semple, Heard and Brouillet (2003) includes x = 9, 8, 7, 5 and 4 species of asters native to North America. A few species are native to South America and several species are naturalized in Europe and scattered locations around the globe. This is the largest group of asters and the most common throughout North America. These are the asters with paniculiform inflorescences and phyllaries with a more or less diamond shaped darker chlorophyllous zone, with considerable variation in degree of leafiness and size of the chlorophyllous zone.

The subtribe is monophyletic and sister group to the clade including Eurybia, Herrickia, Triniteurybia and the Machaerantherinae (Brouillet, Allen, Semple and Ito 2001; Brouillet, Urbatsch and Roberts 2004; e.g. Machaeranthera, Xanthisma). Subtribe Symphyotrichinae includes a number of groups of asters that have been treated as separate genera (Nesom 1994), as subgenera and sections within Aster in the polyphyletic broad sense, and as subgenera within Symphyotrichum (Semple et al. 1996). Semple et al. 2002 recognized five genera: Canadanthus (x=9; 1 sp.); Ampelaster (x=9; 1 sp.), Almutaster (x=9; 1 sp.), Psilactis (x = 9, 4, 3; 6 spp.) Symphyotrichum in the strict sense (x=8, 7, 6, 5, 4; ca. 90 spp.).