Fairy ring

Lore & Background

The mycelium of a fungus growing in the ground absorbs nutrients by secreting enzymes from the tips of hyphae, breaking down larger molecules in soil into smaller ones absorbed through hyphae walls. The mycelium moves outward from the center, and when nutrients in the center are exhausted, the center dies, forming a living ring from which the fairy ring arises. Two theories exist regarding the process: one states a fairy ring begins from a spore from the sporocarpus; the other, based on Japanese investigations of Tricholoma matsutake, shows that rings could be established by connecting neighboring oval genets of these mushrooms, which continuously grow about the center.

One manifestation of fairy ring growth is a necrotic zone where grass or other plant life has withered or died. During a dry year, these zones are caused by mycelia coating the roots of grasses and herbs. Fungi can deplete soil of readily available nutrients such as nitrogen, causing plant discoloration, and some fungi produce chemicals like gibberellins that affect plant growth, causing rapid luxuriant growth. Long-term observations on Shillingstone Hill in Dorset, England, suggested the cycle depended on the continuous presence of rabbits, which crop grass short and produce nitrogen-rich droppings, allowing mushrooms to grow through competition.

There are two generally recognized types of fairy ring fungus: tethered (mycorrhizal, in woods) and free (saprotrophic, in meadows). About 60 mushroom species can grow in the fairy ring pattern, including the edible Scotch bonnet (Marasmius oreades). One of the largest rings ever found is near Belfort in northeastern France, formed by Infundibulicybe geotropa, with a radius of about 300 metres and thought to be over 700 years old.

Reader's Guide

Fairy rings are significant as a natural phenomenon that bridges biology and cultural history. Biologically, they illustrate fungal growth patterns, nutrient cycling, and symbiotic or saprotrophic relationships with plants and soil. The rings can alter grass growth, creating necrotic zones or rings of dark green grass, and can persist for centuries, as seen in rings over 700 years old in France. Culturally, fairy rings have been central to Western European folklore, particularly in Britain, Ireland, Scandinavia, and Celtic regions, where they were attributed to the dancing of elves or fairies, or linked to witches and the Devil. Names such as 'witches' circles' in French and 'Hexenringe' in German reflect these supernatural associations. European superstitions routinely warned against entering a fairy ring, with beliefs ranging from losing an eye to being put in thrall to illusions. The folklore persisted into the 20th century, with stories in Wales and Scotland of people joining fairy dances. Fairy rings thus serve as a case study in how natural phenomena are interpreted through cultural lenses, blending empirical observation with myth.

Did You Know?

• Fairy rings are also known as ronds de sorcières ('witches' circles') in French and Hexenringe ('witches' rings') in German.
• One of the largest fairy rings ever found, near Belfort in northeastern France, has a radius of about 300 metres and is thought to be over 700 years old.
• Long-term observations on Shillingstone Hill in Dorset, England, suggested that the fairy ring cycle depended on the continuous presence of rabbits.