Cheryll Butler, age 14, of Sioux City, Ia., for her question:
Are lichens of any use?
Many of these modest plants grow on bare boulders. They look like rock paintings of pastel tinted flowers and foliage. Other lichens grow on the ground, sharing the soil with the hardiest types of moss. There are lichens in cool, warm and tropical zones, and some thrive under the Arctic snows.
Our luxurious planet is clothed with countless assorted plants and populated with a million or so different animals. Every one of its plants and animals carries on a give and take relationship with its neighbors. Each has its own special place in the balance of nature that enables the Earth to change, replenish itself and keep going. Each plant and animal not only has a use, but it is necessary to the well being of a number of other plants and animals.
The little lichens do not look like important plants. A few varieties spread like tinted pictures on the faces of bare rocks, but most of them live half hidden in sheltered places close to the ground. They may spread in flat rosettes or mossy carpets of straight or branching spikes. Some varieties look like miniature sponges and others like frilly pour pours of clustered foliage. But we need a magnifying glass to study them.
The humble little plants thrive in many places where larger and more complex plants cannot make a living. Reindeer moss is one of several lichens that thrive under the Arctic snows. These little plants provide food for hungry reindeer and other plant eaters of the frozen north. Iceland moss is a lichen that grows on bare, cold mountains of Iceland. It has medicinal qualities, and northern peoples often gather it to make bread. In many parts of the world other lichens are used to make textile dyes.
But the most important function of the lichens is the creation of soil. Many of them thrive on bare rocks with nothing to support them but the moisture of the air. In growing, they produce acids that weaken and break up solid stones. And powdered rock is the first ingredient needed to make soil. The lichens of barren regions are busy helping nature provide the rich soil needed by the plant world that grows to provide oxygen and food for the animal kingdom. The hardy little lichens that grow alone in barren regions perform one of the most useful, of all jobs in the complex balance of nature.
Each and every lichen is a team of two different plants, living together on a give and take basis called symbiosis. One partner is a moisture loving, sugar making alga. The other is a spongy, moisture storing fungi unable to manufacture its own plant food. The alga has chlorophyll to make food from sunlight, air and water. The fungi has no chlorophyll. The fungi soaks up and stores pockets of moisture for the thirsty alga, and the alga makes enough plant food for itself and its partner.