Garden Variety: Learn to love lichens

[USA] What’s to like about lichens? Some people would apparently say a lot, as California became the first state to designate an official lichen on Jan. 1, 2016. Kansas has its share of interesting lichens, too. You just might have walked by without noticing them.

Lichens are small, slow-growing organisms that can grow on just about any undisturbed surface. You might find them on rocks, tree trunks, old bricks, etc. Describing them is difficult because they come in so many colors, shapes and sizes.

For example, the lace lichen (the new state lichen of California) grows in an intricate lacy net that hangs from tree branches in coastal regions. In the Midwest, lichens might look more like a web of oddly-shaped rubbery leaves, peeling paint, or moss.

More than a lichen’s appearance is unique. The way they grow is unusual because they are composed of two to three specific organisms that grow together to form one.

The key component of a lichen is always a fungus. The second organism may be an algae or a cyanobacteria (blue-green algae). Sometimes both an algae and a cyanobacteria are associated with the fungus.

Either way, the fungus is said to “farm” the algae or cyanobacteria because it relies on them for food. The fungus provides moisture, structure, and protection for the algae or cyanobacteria.

Sometimes gardeners are concerned about lichens growing on tree trunks because they fear the lichens affect the health of the tree. Lichens only use trees and other structures for support though. If they seem more prolific on a dead branch than a live one, the most likely reason is simply that there is more light available on the dead branch than the one shaded by leaves.

California chose to designate a state lichen to bring attention to lichens’ role in the ecosystem. First, lichens are sensitive to air pollution, so they are being used to monitor air quality in the state. Lichens are also known as an early colonizer on disturbed sites, and they provide food, nesting material, and cover for animals and insects.

Lichens are also used for natural dyes in some regions, and recent research suggests lichens may be useful in medicine. Certain types of lichens have antibiotic properties and have been used in that capacity for many years. Lichens that resemble miniature plants are sometimes dried and preserved for use in model train displays and architectural scale models.

Most lichens grow less than a millimeter per year, and they are found on all seven continents. Some are considered to be among the oldest living things on earth.


Photo: Lichens, which consist of a fungus and an algae or cyanobacteria growing together, are a common sight on tree trunks and other outdoor surfaces. Far from being harmful, they have a number of practical uses, from testing air quality to coloring fabrics.

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