This guide addresses the challenge of identifying non-flowering plant species in the field by providing a comprehensive visual reference for over 750 ferns, mosses, and lichens. The authors, Hans Martin Johns and H. Martin Jahns, utilize their botanical expertise to curate a selection of species specifically chosen for their visibility to the naked eye. The text integrates structural descriptions with ecological context to assist both amateur naturalists and students in navigating the complex taxonomy of these often-overlooked plant groups.

The subject matter points to a highly specialized and dense reference tool intended for field use by serious naturalists and botany students. Its focus on macroscopic identification suggests a practical, accessible approach to a traditionally technical field of study.