The known macrolichen flora of Florida consists of 150 species in 25 genera. The present study is based on some 6,000 specimens, most which were collected from 1964 to 1968. A complete description, including salient morphological and chemical traits as well as the local geographic tribution, is given for each species. Keys are provided for the genera and for the species in each genus. Although the keys and descriptions are based Florida specimens, the general treatment should be applicable to the flora adjacent regions in the coastal plain of the Deep South. Most of the macrolichens of Florida fall into ten categories with regard their worldwide distribution: species endemic to Florida; pantropical species; widespread species; exclusively North American species; North American- tropical American species; North American-European species; North American- Asian species; North American-tropical American-Asian species; North American-tropical American-European species; and north temperate species. though five species, Cladonia abbreviatula, C. botryocarpa, C. perforata, Leptogium floridanum, and Ramalina paludosa, are known only from Florida, the degree of endemism among the macrolichens is low. In comparison with that of of some other regions of eastern North America, is not particularly rich. Eighty-nine species are sufficiently common enough for a reliable determination of largest number, 44 species (e.g., Cladonia occur throughout the state. Thirty-two species (e.g., Cladonia polycarpia), ten species have Dirinaria purpurascens), six species have a tion (e.g., Cladonia prostrata), and five almost exclusively coastal. Maps of the Florida are provided as examples of the distribution macrolichen flora. Four Caribbean species, Cladonia sandstedei, dasypoga, and R. dendriscoides, are reported the first time. Xanthoria is reported from second locality was discovered for the species previously known only from the In keeping with certain newer taxonomic the Physciaceae, it is proposed that several Physcia, a clearly polyphyletic group at aegialita and P. purpurascens are transferred Physcopsis.