Platismatia glauca is a common and widespread species of corticolous (bark-dwelling), foliose lichen in the family Parmeliaceae.
It was first formally described by Carl Linnaeus in his 1753 work Species Plantarum. William and Chicita Culberson transferred it to the genus Platismatia in 1968.
Platismatia glauca can acclimate to large variations in the availability of environmental nitrogen. It efficiently assimilates increased nitrogen into its thallus, increasing the size as well as the photosynthetic capabilities of its photobiont.
Several secondary metabolites (lichen products) have been isolated from the species, including the nor-triterpene ketone, 30-nor-21α-hopan-22-one, the depsides atranorin and chloroatranorin, and the aromatic compounds methyl β-orcinolcarboxylate and chloroatranol. Other compounds in the lichen are salazinic acid, β-orcinol carboxylic acid, 3-hydroxyphysodalic acid, physodalic acid, and physodic acid.