
                         Roanoke Times
                 Copyright (c) 1995, Landmark Communications, Inc.

DATE: SUNDAY, December 4, 1994                   TAG: 9412030009
SECTION: EXTRA                    PAGE: 5   EDITION: METRO 
SOURCE: PATRICIA HELD
DATELINE:                                 LENGTH: Medium

THERE'S MUCH TO ADMIRE ABOUT THE LOWLY LICHEN

Lichens are the most obliging of plants. True pioneers, they grow where other plants will not. They do not cause us to sneeze or get a rash, and their needs are few. Lichens require only the smallest amount of water to survive, and they can withstand the coldest weather.

Lichens went unnoticed for a long time. The great Swedish botanist, Carl Linnaeus, considered them unworthy of recognition. It was not until the middle of the 18th century that the true nature of lichens was discovered.

Since then, more than 20,000 species have been identified, and they have been found growing in nearly every type of environment.

A lichen is not a simple one-plant organism. What looks like a single plant actually is a highly integrated association of two different plants, a fungus and algae, living closely together. A century-old botany manual refers to this relationship as an ``unnatural union between a captive algal damsel and a tyrant fungal master.''

Lichens were described and named long before their dual partnership was discovered. It was not until the mid-1800s that the possibility was suggested, and the theory was only accepted in the early 20th century.

Scientists are still not quite sure whether this association is mutualistic - whereby both partners benefit from the association - or parasitic upon the algae. Some researchers believe that both species benefit by their relationship. The ``inside'' part of the lichen is algae. It produces food through photosynthesis and gives the lichens their greenish color.

The ``outside'' plant that is mostly visible to us is a fungus, which uses carbohydrates produced by the algae. In return, the fungus provides protection and moisture for its fragile partner. The fungus also controls the shape of the lichen and has root-like threads for attachment to soil, wood or rock. Recent studies indicate a different type of relationship. The fungus parasitizes on the algae, but this parasitism is slow and controlled enough so that the algae continue to thrive.

Lichens have some economic importance. In the Northern regions they provide food for reindeer, and in times of famine humans have used them for food. Some lichens are a source of ``cud bear,'' a blue or red dye used to color fabrics and drugs. Others produce litmus, the chemical used in litmus paper. A few lichens are very important to the perfume trade: They are used to make the many ingredients in perfumes all evaporate together to produce a pleasant effect.

Lichens are extremely sensitive to their environment and are reliable indicators of atmospheric pollution. Since lichens lack roots, they obtain most of their nutrients from dust in the air. They easily succumb to pollutants. Large metropolitan cities are noticeably lacking in both numbers and varieties of this plant.

Lichens are also victims of atomic fallout; they are not protected by the dilution of these elements that takes place in the soil. Studies reveal that Laplanders, who have diets consisting primarily of reindeer and caribou, have higher concentrations of radiation in their bodies. Although they are thousands of miles from atomic activity, the lichens that the animals eat have absorbed high levels of radioactivity, and in turn have transferred it to the Laplanders.

Lichens exhibit their greatest value with the role they play in succession. As pioneer plants, lichens grow in barren areas where no other plants can survive. They have a weathering effect on rocks, breaking them apart to form soil. Then other small plants can take hold, enrich the soil and prepare for the larger plants that will follow. The growth habits of lichens also prevent wind and water erosion on barren and waste areas.

Now that the leaves have fallen and most of the colors are gone, these tiny plants, which have gone unnoticed throughout the growing year, begin to appear. Their subdued colors of green, orange and yellow form beautiful patterns on the bare earth, rock and bark of trees.

Of the species found growing in our area, the most obvious are the pixie cup and shrubby reindeer lichens. Probably the showiest of all our local species are the British soldier lichens, with their pale green stalks and vibrant red fruits reminiscent of the scarlet tunics that were worn by the British during the American Revolution.

Patricia Held is a Bedford County free-lance writer and author specializing in natural history.

by CNB