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Oreostemma E.L. Greene is small western North American genus of three species of white to pink-purple rayed asters with a chromosome base number of x=9. The three species occur at mid to high elevations in the Rocky Mts., Cascade Mts., and Sierra Nevada. The genus is distinguished by its habit; basal rosettes with solitary scapose heads.
Arthur Cronquist monographed this group of asters for his Ph.D. thesis (published in 1948 as a part of Aster). Nesom (1993, 2000) reviewed the genus more recently and in Flora North America (Nesom 2006 FNA).
Brouillet et al. (2004, 2009) and Seliah and Brouillet (2008) found the genus to be related to Herrickia and Eurybia or basal in the Symphyotrichinae-Eurybia-Machaerantherinae clade.
The classification here follows Nesom (2006):
- Oreostemma alpigenum
- Oreostemma elata
- Oreostemma peirsonii
Brouillet, L., L. Urbatsch and R.P. Roberts. 2004. Tonestus kingii and T. aberrans are related to Eurybia and the Machaerantherinae (Asteraceae: Astereae) based on NRDNA (ITS and ETS) data: reinstatement of Herrickia and a new genus, Triniteurybia. Sida 21: 889-900.
Nesom, G.L. 2006. Oreostemma Greene. pp. 359--361. In Flora North America Editorial Committee, eds. Flora of North America. Vol. 20. Asteraceae, Part 2. Astereae and Senecioneae. Oxford University Press, New York.
Selliah, S. & Brouillet, L. 2008. Molecular phylogeny of the North American eurybioid asters, Oreostemma, Herrickia, Eurybia, and Triniteurybia (Asteraceae, Astereae) based on the ITS and 3’ETS nuclear ribosomal regions. Botany 86: 901-915.
revised 3 February 2014 by J.C. Semple
© 2014 J.C. Semple, including all photographs unless otherwise indicated