Lichen Spotting
As gardeners, we have few obvious uses for them, but their miniature beauty exists all over the globe. While their many beautifully complex clashes and collages of shapes and colours seem bland at a distance, they are fabulous on closer inspection. I hope this up-close primer will spur some interest in lichens for gardeners and non-gardeners alike.
Lichens are some of the most interesting life forms on the planet. Each species is the result of a combination of fungi and algae, living together in a symbiotic relationship. For more information about the biology of lichens, I suggest you follow one of the following links.The Biology and Symbiosis of Lichens is a great page for people with a beginning interest in Lichens. For more in-depth information on lichen biology, visit Pierre Volpe's Lichen Site.
In Vancouver, B.C., Canada, the last couple of weeks have been ripe for lichen spotting. The fruiting bodies of the fungi are at their peak, and the algae that live with them just LOVE the rain (like all other Vancouverites).
Lichens were first pointed out to me when I was about seven. This was during a walk around Vancouver's stunning Stanley Park seawall. The venerable disks of Rhizocarpon geminatum still cling to the basaltic rock face today. Has the lichen shrunk, or am I just getting bigger?
A short walk down many local back alleys reveals tiny Calcidium viridae growing on dew-moistened cedar telephone poles. Note the interesting formation of black fruiting bodies of this common fungus-algae combination.
You wouldn't find lichens in every city. Most lichens will not tolerate even medium levels of air-borne pollutants. Because of this sensitivity, lichens play an important role in testing air pollution. In industrialized areas, the health of lichens can be mapped and any change in air quality can be monitored. In Vancouver, we should feel very fortunate to have the bulk of our air pollutants blown by Pacific winds to the suburbs and beyond.
Apart from highly polluted areas, lichens can grow almost anywhere in the world. Some species are able to colonize very hot, harsh environments like deserts while others survive in the cold, dry alpine environments where most other plant types are not able to exist.
In extreme conditions, lichens may only grow a fraction of a millimetre a year, while temperate and tropical lichens may make annual growths of as much as one centimetre.
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