Includes a key to North American species.

Before the compiling of this volume, the published results of research carried out with respect to this lichen genus were widely scattered, in many different languages, and often very difficult to locate or translate.

Uses keys and line drawings for the identification of most British and Irish species of the lichen genus cladonia.

This work has been selected by scholars as being culturally important, and is part of the knowledge base of civilization as we know it. This work is in the "public domain in the United States of America, and possibly other nations.