Intermountain aster (Symphyotrichum ascendens) is most commonly found along seasonally dry streams in the Boise foothills and mid-elevations, less commonly along the Greenbelt and in the Conifer Zone, sometimes occurring on mid-slope sites with subterranean seepage.  The most diagnostic feature is the graduated or shingle-like involucral bracts (aka phyllaries), with at least the lowest/outermost blunt-tipped and much shorter than the uppermost.  Stems are usually subglabrous or with scattered appressed hairs, inflorescences are generally narrow with relatively few heads, leaves are narrow, and plants are relatively short to medium-sized.  Ray flowers are most often various shades of purple or lavender, but populations in the conifer zone are often white.

Look for intermountain aster along Bob’s Trail, Old Pen Trail, Homestead Trail, Hulls Gulch Interpretive Loop, and similar locations from late August to early October.

The previous spelling of the species epithet as “adscendens” has now been corrected to “ascendens”, for nomenclatural reasons.