This book constitutes a unique, encyclopedic reference work that systematizes and categorizes for the first time in such comprehensive fashion all known fern spores. The dominant feature of the work are the over 350 plates of electron micrographs showing the morphological characteristics of typical representatives of each spore type. The purpose of the book is to provide a complete survey of the available data on the fine structure and composition, development, and evolu- tionary significance of different types of spore walls, which have proven resistant to fossilization throughout geological ages. The classification system developed by the authors as the result of many years of research will be a point of reference, if not "the" systematic basis, for all future publication on the subject. The book will be of great interest to all botanists and evolutionary biologists working with spores and/or ferns, but it will also be of major importance to paleobotanists, palynologists, stratigraphers, and exploration geologists, since the focus of this treatise is on spores as highly adapted and longlived reproductive forms.