Porter's Aster, Smooth White Aster

Symphyotrichum porteri (A. Gray) G.L. Nesom is the foot hills and near the Rocky Mountain Front Range in eastern Wyoming, Colorado and New Mexico. It has glabrous leaves without axillary clusters, scabrous margins, and array branches ascending, peduncle bracts 1–3; ray laminae 6.8–12 × 0.7–1.8; disc florets (30–)40–75(–103) (Brouillet et al. 2006 FNA)  The species is diploid (2n=16).