Based on the acclaimed reference Lichens of North America, this resource for the classroom, field, and laboratory presents updated and expanded keys for the identification of over 2,000 species of lichens indigenous to the continent, twice the number covered by previous keys. The book includes a glossary 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.--COVER.