Reading the Lichen Thallus

Like any good book, a lichen thallus contains a wealth of information.

But first one has to learn to read.

Lichenologists have long recognized that many lichen species are tremendously variable – much more so than their counterparts in other taxonomic groups: birds, mammals, mushrooms, wildflowers. Why this is isn’t hard to understand. Having no roots or other hidden parts, lichens are obliged to wear their biographies, so to speak, on their shirtsleeves: what you see is what you get.

To put it another way, lichens are the outward face of a dynamic relationship between two or more partners: fungi and algae. Like all relationships, the lichen relationship is easily altered by the least shift in environmental conditions. In effect this means that lichens represent a nearly perfect convergence of form and function. The particular outward details – colour, shape, thickness, etc – of a particular thallus is therefore a register of the kinds of environmental factors under which it formed.

Reading the thallus is lichenological gold: a new way of thinking about landscape: a means of acquiring ever more nuanced insights into environmental process by simply deciphering it through the myriad forms of the lichen thallus. In the absence of detailed instrumentation, reading the lichen thallus can help us better understand the inroads currently being made by climate change. Reading the lichen thallus is one of many themes developed in our upcoming book Ways of Enlichenment.

Watch this webpage for postings of papers, essays and musings pertinent to the art (science?) of lichen literacy. Also keep an eye out for announcements of future field meetings. Beginning in 2010, Trevor Goward will host an annual “Lichen literacy” field meeting out of his home in southern inland British Columbia. Details will be made available here and in the Northwest Lichenologists newsletter. Email us if you would like to be kept notified. Space is limited so be sure to sign up early.