Lichen floras at two sites on the Aquarius Plateau were compared; including a high elevation site located at the crest of the Boulder Mountain plateau (3353 m) and a mid-elevation site along the base of the same mountain (2347 m). Lichens were collected from all available substrates at both sites. A total of 30 genera and 49 species are reported from the upper site with 21 genera and 35 species from the lower site. Fifteen genera and ten species were common to both sites. Overall, the two most common genera (Xanthoparmelia and Rhizoplaca) showed greater diversity and abundance at the mid-elevation site. Of the six Xanthoparmelia spp. identified during the course of this study, three were common to both sites; however, Xanthoparmelia plittii and Xanthoparmelia mexicana were restricted to the lower site while Xanthoparmelia wyomingica was found only at the upper site. Two Rhizoplaca spp. (R. chrysoleuca and R. melanophthalma) were abundant at both sites; however, Rhizoplaca peltata was rare to common at the lower site and rare at the upper site. These differences in species distributions and abundances emphasize the influence habitat has in determining the distribution of species across natural landscapes.