However, when these creatures invade landscape trees and shrubbery, homeowners frequently become concerned about possible damage to landscape plants. However, the appearance is that of a single plant. Lichens manufacture their own food and grow on soil, on rocks, and trunks and branches of trees and shrubs. They occur in several forms such as crusty gray, green, yellow, or white growths. Some are leaf-like, others resemble a tuft of horse hair hanging from branches.
Lichens are amazing creatures for other reasons as well.
They frequently serve as a source of food for snails, mites, and insects. In subarctic regions, lichens are a food source for reindeer and caribou. In hard times, lichens have served as a source of food for man, such as when Washington's troops at Valley Forge used lichens as a soup thickener. Today, lichens still serve as a source of natural dyes used wool and other clothing materials. In the home landscape, lichens most often appear on plants that for some reason are in a poor or declining condition.