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United States Department of Agriculture

Agricultural Research Service

Ain't Nothin' Like Lichen - Text only

Ain't Nothin' Like Lichen

Lichens ("lie-kins") are life forms that can grow in some of the most extreme environments on Earth—from the frozen arctic tundra and scorching hot deserts, to rainforests and steep cliff faces.

Lichens are a combination of two organisms living together in a relationship called "symbiosis" (SIM-bye yoe-sis). The two partners are algae (like stoneworts, seaweed, or pond scum) and fungi (like molds, rusts, or mushrooms).

How they form a lichen is one of the great puzzles in biology. But their partnership is a successful one.

There are 13,000 to 30,000 lichen species worldwide. Many are quite beautiful and colorful. Once joined, an alga begins using sunlight to make sugars as food for both itself and its fungal partner. The fungus' job includes protecting them both from intense sunlight and other stresses.

Lichens or the chemicals they make have been used to make all sorts of interesting products, including dyes, cosmetic ingredients, and medicine.

Damage to lichens can show the effects of pollutants in air or water. Their loss shouldn't be overlooked. They help break down material that keeps soil healthy, and they provide food and shelter for all sorts of creatures—big and small. They're also used as packaging and decoration, including for model train towns.

So love those lichens, their partnership helps us all.

—Adapted by Jan Suszkiw, Agricultural Research Service, Information Staff.

For more information on lichens visit:

The U.S. Forest Service

The British Lichen Society


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Last Modified: 4/12/2013
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