These colourful encrustations on rocks, trees, walls and gravestones are an incredible natural phenomenon.
One of the longest living organisms on the planet, lichens grow very slowly. Lichens are symbiotic organisms made up of a fungus (which transports nutrients), an algae (which contains chlorophyll to made food by photosynthesis) and sometimes a cyanobacteria which also produces food from water, carbon-dioxide and sunlight. They don’t have a root structure, and are able to shut down their metabolism during periods of extreme heat, cold and drought. They are a food source for many insects and birds.
Ireland is very rich in lichens, with over 1,100 recorded species.
Lichens are a good indicator of pollution levels, and if there are no lichens on the trees this means the air quality is very poor.
With over 500 biochemical compounds, lichens were used in dyes, poisons and medicines in traditional societies. Nowadays they are used as a fixative in the perfume industry.
Killarney National Park and the Burren are great places to see a wide variety of lichens. See Paul Whelan's Lichens of Ireland (The Collins Press) for more information.
