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.

Oil bodies, found in cells of most leafy liverworts, provide valuable taxonomic characters which are often critical for determining species. Despite the regular presentation of oil body data in species descriptions, no standard protocol for recording oil body number has been developed until this time. A standardized protocol has been developed using a transect of cells defined by an ocular micrometer.

A bryophyte inventory is reported for the Gila Cliff Dwellings National Monument (216 hectares) in southwest New Mexico. We made 250 bryophyte collections from this rugged terrain, among which we identified 51 species of mosses belonging to 14 families. We also found four liverwort species in three families. No hornworts were seen.

The thallose liverwort Riccia rhenana is one of three species in the taxonomically challenging “Riccia fluitans” complex that typically occur as floating aquatics. Taxonomic uncertainty has made it difficult to determine the geographical distributions and ecological affinities of these species. A further complication is that these plants are widespread and common in the aquarium trade, raising the possibility of human introductions. Recently we collected R. rhenana from a highly distinctive habitat: a cold, clear, high-flow spring in the Chattahoochee National Forest in northwest Georgia. Subsequent checking of earlier collections revealed that this species appears to be restricted to these unusual habitats within a small area in the northwestern corner of the state and in the vicinity of Pine Mountain in westcentral Georgia. We urge other collectors in the Southeast to seek additional localities for these plants and to reexamine earlier collections with these geographical and ecological correlates in mind.