Stiff-leaved Asters, Ankle-asters
Ionactis E.L. Greene is small North American genus of five species (Nesom and Leary 1992) of pink to purple rayed asters with a chromosome base number of x=9. The four species occur at mid to high elevations in the Rocky Mountains and Cascade Mountains. One species occurs in eastern North America. The genus is distinguished by its stiff leaves, narrow phyllaries with chlorophyllous zone restricted to narrow bands along the raised midrib, and fusiform achenes with a quadruple pappus of a short 2° outer whorl, a 2° inner whorl of intermediate length, and two 1° whorls of long bristles, the 1° inner whorl being clavate (Semple & Hood 2005).
Brouillet, Allen, Semple and Ito (2001) found the genus to be basal in the clade including subtribe Symphyotrichinae, Oreostemma, Herrickia, Eurybia and Nesom's subtribe Machaerantherinae. Four species of Ionactis formed a clade that was one branch of the large unresolved near basal polytomy in the phylogeny of the Astereae (Brouillet et al. 2009).
Five species are rcognized following Nesom (2006 FNA):
- Ionactis alpina (syn: Aster scopulorum)
- Ionactis caelestis
- Ionactis elegans
- Ionactis linariifolia
- Ionactis stenomeres
revised 10 February 2014 by J.C. Semple
© 2014 J.C. Semple, including all photographs unless otherwise indicated