Identification: DeBolt and McCune report 4 species of Psora from Glacier National Park (with the following characters from Brodo, 2001, pp.597-604): decipiens (squamules bright brick red to orange brown … 1-6mm in diameter) globifera (squamules shiny reddish brown … 2-5mm across) himalayana (squamules medium to dark reddish brown … 1-3mm wide) nipponica (squamules olive to greenish brown … (2-)3-6(-10)mm across … on edge and curled inward with the pale lower surface exposed) Hmmm. The first three descriptions mention the correct color, and the fourth the correct size and shape. DeBolt and McCune also mention that the first two species are occasional in the park (with the second generally in crevices), the third is in a specific elevational band, and the fourth is common. Sharnoff's photos indicate another interesting difference: the tendency of single squamules of Psora nipponica to support a small heap of apothecia. That is surely the case in the present instance, so I follow Jason in voting for Psora nipponica.