From Tree Life 208.  June 1997

According to a recent article in National Geographic, lichens are attracting new attention for their medicinal, decorative and pollution detecting properties.
Despite their plant-like form, lichens are not plants. They are a symbiotic combination of a fungus with an algae and/or cyanobacteria. Fungi, algae and bacteria now occupy classifications of their own, in addition to the two traditional “kingdoms” of plants and animals.
The pigments, toxins and antibiotics contained in lichens have made them useful to people in many areas of the world for centuries.
Lichens have provided dyes for the Navajo Indians’ rugs, Scottish tweeds and the royal purple of Roman times.
Their medical properties have been utilised in teas, skin salves and modern antibiotic creams. Some lichen species are food for animals and humans.
Growing almost anywhere with a stable surface – from stained glass windows of cathedrals, to the backs of Galapagos tortoises – lichens are among the world’s oldest living things, making them useful for dating artefacts or geological events such as the retreat of glaciers.
Because of their sensitivity, lichens are indicators of air quality, absorbing pollutants that can be measured by chemists.
Pollution is a threat to lichens, even in the Arctic. Fallout from Chernobyl contaminated lichens eaten by reindeer. Tragically the animals had to be destroyed.

-A J MacFarlane  From an article in National Geographic dated February 1997.