Lichens are complex life forms that are the result of a symbiotic partnership between multiple organisms, usually a fungus and an alga. Though often overlooked or mistaken for other organisms (like moss), lichens are a critical part of each ecosystem they inhabit and are important sources of food, absorbers of carbon dioxide and biomonitors that help scientists detect air pollutants, among their many other functions. Written by one of the world's foremost lichenologists, Lichens is an extensive guide to lichen species of Ontario and central parts of North America, but many of the featured lichen species are found in other parts of the world, including Scotland and Scandinavia. Lichens presents photographs and detailed information on over 450 species of macrolichen, which are types of lichen with large thalluses that appear either leafy and lobed or bushy and branched. Because of these qualities, the vernacular names of the species often take on colourful and intriguing descriptions, such as Witch's Hair, Toy Soldiers and Yellow Specklebelly. Each entry details the lichen's composition, habitat, distinctive features, range information and comments about the lichen's application or significance. The book also features an extensive introductory section about lichen basics, a photographic summary of the genera, keys to the genera, an extensive list of references and an illustrated glossary. In short, the amount of detail included in Lichens will be sure to satisfy both the serious lichenologist and the casual nature lover. The format and binding make this ideal as a field guide as well as a comprehensive reference.