The morphological and chemical characteristics of Physcia aipolia and P. alnophila are compared, and a distribution map for northern North America is presented. The two taxa are shown to be both morphologically and chemically distinct, although spore size and lobe width overlap too broadly to be definitive in the absence of correlating characters such as presence of apothecia almost to the lobe tips and absence of fatty acids and triterpenes other than zeorin in P. alnophila. In North America, P. alnophila has a widespread distribution in boreal to subarctic Canada. Physcia aipolia appears to be a more temperate species extending northward in the prairies and almost absent in the Pacific Northwest.