Created in response to requests from longtime users, this addition to the acclaimed reference to North American lichens compiles updated and expanded keys for the identification of these fascinating organisms. An ideal laboratory resource, it covers over 2,000 species of lichens indigenous to the continent. There is no comparable volume available for classroom, workshop, or private use. A glossary is illustrated with photographs by Sylvia Duran Sharnoff and Stephen Sharnoff and drawings by Susan Laurie-Bourque, all from the original book. The revised keys are an indispensable identification tool for botanists, students, scientists, and enthusiasts alike.