Shining a light on one of the most overlooked ecologically significant organisms, this practical pocket-guide introduces readers to the species of lichens found around Britain. Responsible for introducing the term symbiosis to the natural sciences, lichens play a vital role in air quality monitoring, soil formation, and forest health. With clear descriptions, identification tips, and notes on habitat and distribution, Peter Gray provides a focused introduction to the fascinating world of these symbiotic organisms. This new volume is an extract from Holmes' seminal British Fungi, Lichens and Mosses (1886), republished in a smaller edition for field use and botanical education. Perfect for students of plant sciences, amateur ecologists, and professionals engaged in conservation and biodiversity recording.