Dotty Hardberger, age 10, of Thibodaux, La., for her question:

Why do mushrooms grow in a fairy ring?

Mushrooms are fungus plants with no green chlorophyll to make their food from air and water. They must depend upon prefabricated foods made by other plants. For this reason they must grow in soil rich in decaying vegetation. One of the best spots is the rotting stump of an old tree trunk.

Sometimes the stump has decayed to ground level and becomes overgrown with grasses. The tangled threads which are the main plant of the mushroom grow under the soil around the edge of the old. Stump. In warm, wet weather they poke their chubby umbrellas up through the grass. Because the plant grows around the old tree, the mushroom buttons form a circle, a fairy ring in the meadow