Why Do Mushrooms Grow in a Circle?

Some types of mushrooms can be frequently found growing in circles, which are commonly known as "fairy rings." Mushrooms are the fruiting part of the fungus, which actually grows underground and is called the mycelium.

Mushrooms are fungi, which technically are not plants. They have their own kingdom in the world of scientific taxonomy. Fungi live in the soil or in wood, and their cell walls are made from chitin, just like insects. Mushrooms are only the fruit of the fungi; the fungi itself is called the mycelium.

Fungi do not produce chlorophyll because they aren't plants. They are important decomposers, and help break down wood and other organic debris. During decomposition, fungi return valuable nitrogen back into the soil, which is necessary for new plant growth.

Marasmius oreades frequently grows in rings, and is commonly called the fairy ring mushroom. It is an edible mushroom. Other mushrooms that grow in rings are Chlorophyllum molybdites (chloro means "green") and Agaricus campestris, the meadow mushroom.

A mushroom ring may make the grass inside the ring greener as the fungi produce nitrogen for the soil. Sometimes large amounts of mushrooms may make it difficult for water to reach the grass roots, which will cause the lawn to turn brown. The condition is usually temporary.

Fairy rings were thought to be caused by fairies who danced the night away. When they became tired and wanted a place to rest, they went to the fairy king and asked for something to sit on, and he gave them mushrooms for seats.