Bruce Ryan’s Working Keys to North American Lichens

One of the two most useful references for experienced students identifying North American lichens.
May, Brodo & Esslinger

Over a lifetime of enthusiastic and wide-ranging lichen study, Bruce Ryan amassed a wealth of taxonomic observations on the lichens of North America. In 1994 he synthesized his observations into an informal set of identification keys, which he periodically updated over the next decade until his untimely death in 2004. In Identifying North American Lichens, May et al. (2002) ranked these “working keys” foremost in their list of “twenty most useful” lichen identification references. To be sure, Bruce’s keys represent the only comprehensive set of identification keys to North American lichens since Bruce Fink’s Lichen flora of the United States, published sixty years earlier (Fink 1935).

True to his generous spirit, Bruce Ryan made his keys freely available for the asking – a gesture his lichenological colleagues have continued to honour since his death. The enormous size of his work, however, has made forwarding it by e-mail all but impossible; usually it had to be burned to a CD and then mailed out individually.

In this time of instant internet communication, it seems appropriate to accommodate Bruce’s desire for open access by posting his keys on-line. Taking this step not only makes this monumental work instantly available to all, it also allows Bruce’s original files to be both repackaged for more convenient use and converted into universally accepted PDFs.

Bruce Ryan’s keys are a snapshot of North American lichen taxonomy as it existed in the 1980s and 1990s. Taxonomic advances since then have necessarily rendered some of Bruce’s species and genus concepts a little out of date. Even so, his keys seem destined to remain an invaluable resource for decades to come, especially in regions – most of the continent in fact! – where modern lichen treatments are still lacking. They are likely also to remain a godsend for those of us who from time to time need to brainstorm some unknown lichen find.

We salute Bruce Ryan; and we look forward to the day when his dream of a modern lichen flora for all of North America is finally realized.

Converted into PDF files: (24 Mb) Original WordPerfect format: (3.8 Mb)

Fink, B. 1935. The lichen flora of the United States. University of Michigan Press, Ann Arbor, 426 pp.

May, P.F., I.M. Brodo and T.L. Esslinger. 2002. Identifying North American Lichens: A Guide to the Literature.