The present study investigates the photobiont diversity of the boreal felt lichen, Erioderma pedicellatum. Previously sampled genetic data from Newfoundland were reanalyzed and new sequence data (16S rDNA, rbcLX) of the boreal felt lichen from Alaska (USA), Kamchatka (Russia), and North Trøndelag (Norway) were generated. The highest genetic diversity of the photobiont is found in Alaska and Kamchatka, indicating that these may be the primary sources of the species in the Northern Hemisphere. In Newfoundland, the photobiont of E. pedicellatum was screened on leaves of the symbiotic liverwort Frullania asagrayana and it was found to occur on trees where no other lichens were present, demonstrating that the geographical distribution, and possibly also the ecological requirement of the photobiont of E. pedicellatum, is wider than that of the lichen phenotype. Finally, a postulated association between the occurrence of the vegetatively reproducing Coccocarpia palmicola and the occurrence of the compatible photobiont of E. pedicellatum on the same tree could not be established.