This Festschrift contains 44 lichenological contributions and is published on the occasion of Hertel’s 65th birthday. The 79 contributing authors represent 19 different countries. Lecidiaceae sensu lato are well represented in this book, which covers a vast array of lichens of different sytematic position, growth form, ecological characters and distribution. Various aspects of lichenology are dealt with in this book: anatomical and ontogenetic studies, chemical, physiological and molecular research, analyses of the structure and mechanisms of lichen photobionts, systematic studies, biogeographical studies. The contributions to this Festschrift show the current lichenological problems and progress, but still a lot is unknown of certain groups of lichens, especially the more inconspicuous ones. Only a limited part of the world has been inventoried more or less completely, and also numerous specimens are in the Botanische Staatssammlung München (where Hertel was curator) are still waiting for investigation.