In English This volume focuses on the interaction of lichens with their

substrate, environment and their biogeographic effects.

In seventeen chapters thirty-eight authors present recent fi ndings

and developments in systematics, biodiversity, fl oristic studies

and ecology, as well as newly described taxa, and keys to the

identifi cation of Caloplaca and xanthorioid lichens. Molecular

phylogenetic analyses of several groups and genera are presented,

resulting in an improved systematics of, for example, Caloplaca,

Cladonia, Collema and xanthorioid lichens. The genera Arthonia and

Usnea in Greece (with key) are reviewed.

The volume is dedicated to Prof. Hans Martin Jahns on the occasion

of his 70th birthday, featuring papers on some of his favourite fi elds

of research, among them lichen interactions with their substrate

and environment and lichen biogeography. A brief biography of

Jahns, highlighting his contributions to lichenology, is included in the

chapter on the nine Presidents of the International Association for

Lichenology. Jahns played an important role during the seventies

and eighties with his highly infl uential book, co-authored by Aino

Henssen, entitled Lichenes. Eine Einführung in die Flechtenkunde.

He is well-known for his extensive work and numerous publications

on lichen morphology and ontogeny, particularly the development of

fruiting bodies in different genera.