This investigation of the phylogeny of the lichen genus Parmotrema (Parmeliaceae) includes 43 of approximately 300 species. It also includes one species each of Canomaculina, Rimelia and Parmotremopsis, and two each of Flavoparmelia and Cetrelia, the last being used to root the tree. A parsimony analysis of 54 morphological and chemical characters resulted in 32 most parsimonious trees. The strict consensus tree is largely resolved and shows all terminal taxa, with the exception of the two Cetrelia species, forming part of the ingroup. However, the results were not strongly supported by a bootstrap test and hence should be interpreted with caution. Nevertheless, the very uncertainty of the results indicates that these traditionally used characters, which have been the basis of the classifications of this group to date, are not helpful discriminators at this level. Due to the weak support of the branches, we make no formal proposals, but the parsimony analysis indicates that Rimelia and Canomaculina may be better treated as subgenera of Parmotrema.