Fairy ring

A fairy ring, also known as fairy circle, elf circle, elf ring or pixie ring, is a naturally occurring ring or arc of mushrooms. The rings may grow to over 10 metres (33 ft) in diameter, and they become stable over time as the fungus grows and seeks food underground. They are found mainly in forested areas, but also appear in grasslands or rangelands. Fairy rings are detectable by sporocarps in rings or arcs, as well as by a necrotic zone (dead grass), or a ring of dark green grass. Fungus mycelium is present in the ring or arc underneath.

Fairy rings are the subject of much folklore and myth worldwide—particularly in Western Europe. While they are often seen as hazardous or dangerous places, they can sometimes be linked with good fortune.

Genesis

The mycelium of a fungus growing in the ground absorbs nutrients by secretion of enzymes from the tips of the hyphae (threads making up the mycelium). This breaks down larger molecules in the soil into smaller molecules that are then absorbed through the walls of the hyphae near their growing tips. The mycelium will move outward from the center, and when the nutrients in the center are exhausted, the center dies, thereby forming a living ring, from which the fairy ring arises.