Columbian White-topped Aster
Sericocarpus rigidus Lindl. in Hook.f. is rare in British Columbia and Washington, and Oregon in prairie habitats, dry pastures, dry grassy Garry oak forests with rocky outcrops at 10–200 m ele. (Semple and Leonard 2006 FNA). The species is distinguished by its small stature, entire leaves, and heads with one ray floret. I have no data on a published chromosome count for the species.
The species is of conservation concern throughout its range and is threatened in Oregon.