9706984 Nash A cooperative, international investigation of the lichens (both micro-and macrolichens) of the greater Sonoran Desert region (Arizona, southern California, Baja California, Sonora and Northern Sinaloa) was funded by DEB 92-01111. The project has made progress toward writing a modern lichen flora for use by systematists and other professional botanists as well as decision-makers. Because the Sonoran Desert includes a significant number of Clean Air Act Class I areas, and because lichens are excellent indicators of air pollution, it is anticipated that the flora will have considerable utility to land managers in both the U.S. Forest Service and National Park Services (both U.S. and Mexican). Liason has been established with institutions within Mexico and collaboration and with over 60 prominent lichen systematists worldwide. Publications from this project so far document the discovery of 50 species new to science, and the first records of distribution in the Sonoran Desert for over 200 more. By the completion of the project, the flora will treat over 1700 species in 328 genera.