Most of us have at one time or another looked at a red oak tree and upon closer examination observed green and yellow splotches on the trunk’s bark. These splotches are lichen.
    Lichens are indeed remarkable. They are composed of organisms of two different species that live together in a mutually beneficial way. Being equally beneficial to each other, this symbiotic relationship is between algae and fungi. Lichen fungi are unable to manufacture its food and use algae, which manufactures food by photosynthesis. Lichen algae gets carbon dioxide from the fungus’ respiration. Carbon dioxide and water are needed by the algae as raw material to make its own food.
    Lichens are beneficial to the environment as they “sponge” up everything that comes in contact with it, including air pollution. Too much pollution can harm lichen as in areas of high concentrations of air pollution, lichens will disappear from the surface of trees. This has been used to monitor air quality and upon close examination of lichen, particular pollutants can be identified.
    Beneficial to man, lichens have been used as dyes. Navajo currently use “ground lichen” to dye yarns from sheep. A lichen in what was the eastern Soviet Union was used to treat wounds. In Chinese medicine, homeopathic medicine using lichen is still being practiced. It is estimated that about 50% of lichens have antibiotic properties. Some lichens are edible and some are poisonous.  
DO NOT INGEST ANY LICHEN OR ANY OTHER VEGETATION WITHOUT COMPLETE CERTAINTY IT IS COMPLETELYL SAFE TO DO SO!
    Animals benefit from lichen. It is not uncommon for birds to use lichen material, when available, for nest construction. Animals, such as some flying squirrels, have made their nests completely from lichen. The Yunnan snub-nosed monkey in China subsists almost exclusively from eating lichen. Black-tailed deer from the Pacific Northwest up to Alaska forage on lichen that is under the snow. Smaller creatures use lichen for shelter and camouflage. The best-known lichen eaters, however, are caribou. There have been some caribou fights to the death over this food source.
    I have twice had the privilege of traveling to Canada’s tundra. There, for miles upon miles, there was a floor cover of lichen. It was a beautiful sight. Hardy as they survive in the environment’s harshest climates and fragile as they can not tolerate extremes of pollution and man’s encroachments, there are over 15,000 known species of lichen. Remarkable… indeed.