Book Review

Lichens

By William Purvis
Smithsonian Institution Press, 2000
ISBN 1-56098-879-7

Occasionally at NAMA forays there is a talk or workshop offered on the fungal symbioses called lichens (intimate associations between ascomycetes or, in a few cases, basidiomycetes [mycobionts] and one or more photosynthetic organisms [photobionts], including green algae and cyanobacteria or “blue-green algae”). Although these presentations nearly always are quite popular, few mushroomers pay much attention to lichens as they scour the woods in search of chanterelles, boletes, and morels. However, perhaps this lovely, reasonably priced, introduction to lichens will provide an impetus for more of us to notice and appreciate them, at least when our favorite fleshy fungi aren’t to be found.

Cover

>William Purvis is a lichenologist at The Natural History Museum in London (a wonderful place to spend at least a day if you’re ever in the neighborhood) and is well known for, among other things, being the senior author of the Lichen Flora of Great Britain and Ireland. Although lichens formally are classified as fungi, most of the people who study them do not come from mycological backgrounds. Instead they tend to be botanically oriented and have much in common with folks who study mosses, liverworts, and other so-called lower plants. So not surprisingly, Purvis is a botanist by training and hints of his being not-really-a-mycologist are there in his writing for the careful reader to detect. However, they are of minor consequence and don’t detract from the main purpose of the book.

In 112 pages, Purvis presents a wide-ranging introduction to lichen biology and ecology, some ways in which we use them (for instance, as indicators of air quality), and some practical projects that could be undertaken to learn more about your local lichens. This information is presented in 11 chapters, augmented by preface, index, glossary, and lists of selected books and websites for further information. Coverage includes what is a lichen; how lichens grow, multiply, and disperse; lichen biodiversity; evolution, classification, and naming; ecological role; lichens in forests; lichens in extreme environments; biomonitoring; prospecting and dating; economic uses; and practical projects. Note that this is not an identification guide; those interested in identifying lichens will need to turn to books such as Macrolichens of the Pacific Northwest (reviewed in the Jan/Feb 1998 Mycophile).

The writing is clear and easily grasped, but the key to the book’s success is its superb illustrations. The photographs, nearly all in color, and the other illustrations are very effective and many are beautiful to boot, making the book quite coffee table worthy. As is true in most areas of mycology, there is much we do not know about even the basics of lichen biology and this becomes clear as one progresses through the book. For instance, just how does a fungal spore released from a lichen apothecium find a suitable alga (they are not free-living for the most part) to create a new lichen individual? Does this sort of reproduction occur often in nature, or is reproduction primarily accomplished by asexual propagules such as isidia and soredia (two types of combined bits of fungal mycelium and algal cells that break off and spread the lichen without sexual reproduction)? We just don’t know.

In addition to providing a good introduction to lichens, the book also offers some glimpses into the quirkiness of lichenology (naturally we mycologists have no such quirks). For instance, lichenologists have an extreme fondness for graveyards … and lichen names refer to the fungal partner in the symbiosis, not to the unique organism that the symbiosis represents. This creates a problem when two very different appearing lichens (such as Sticta felix, which is a green algal lichen, and a species of Dendriscocaulon, which is a cyanobacterial lichen) can be found not just as separate individuals, but also as combined organisms, somewhat like having a few orange-bearing branches grow from an apple tree. Thus, it is clear that the same fungus is involved in both. Despite the individual lichens looking completely different, having very different photobionts, and occupying different ecological niches, the rules of lichen-naming dictate that the two lichens bear the same name, Sticta felix. Given that it is becoming increasingly clear that symbioses are the rule rather than the exception in biology, it is time that the rules of nomenclature were changed to accommodate needlessly confusing situations such as this.

Soap-boxing aside, however, this is a very welcome addition to the lichen literature -- accessible, interesting, attractive, and reasonably priced. Hopefully, it will serve to make mushroom-hunters more aware of these intriguing ubiquitous organisms.

— Review by Steve Trudell, Seattle, WA
— Originally published in The Mycophile

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