Fairy Rings

People noticed long ago that chanterelles and some other mushrooms grow in circles, in rings, and that inside and around them a much greener and lusher strip of grass ripples when stirred by even the slightest breeze.

In the Middle Ages, and especially even earlier, this frightened people, because it was explained as hellish circles trampled out by the inhabitants of hell themselves. Witches were often blamed for this – supposedly it was the work of their nocturnal rituals and pranks. For this reason mushroom circles are called "witches' circles", sometimes "witches' rings".

For a very long time, up to the beginning of the last century, it was believed that only supernatural forces could draw such a precise circular line in forests or fields, where the grass also grows in alternation – now lush and deep green, now withered. People were afraid to approach such rings, and only the bolder ones were glad to cut plenty of chanterelles or other mushrooms there.

Only at the beginning of the last century did it become clear that this is not the work of witches or Satan, but an expression of the normal way of life of the common fairy ring champignon (Marasmius oreades) and many other mushrooms. About 15–20 percent of cap mushrooms form so-called "witches' circles". Once it was learned that each year the mycelium grows radially from a germinated spore in all directions by 10–20 cm, and in some mushrooms even more, the cause of the appearance of "witches' circles" was easily revealed.

Many cap mushrooms grow in rings, but not necessarily in the geometric configuration of a regular circle. Particularly regular circles are formed by the fairy ring champignon, the parasol, some plempė, gijabudė and guotė species, funnels and certain other mushrooms that struck terror in the old days.

Strange as it may seem, even today "witches' circles" frighten some people. For example, in 2002 in the Pakruojis district a similar phenomenon was noticed in a large field of grain, and even astrophysicists and psychics took part in explaining it, but mycologists, who could have helped to reveal the essence of the phenomenon, were not invited. Of course, it is very strange why no mushroom rings had been noticed in these fields in earlier years.

The mycelium of many cap mushrooms is perennial and survives for several decades, and the literature describes "witches' circles" that are 600 years old or older. For example, in the prairies of the state of Colorado (USA) in 1917 a 500-year-old "witches' circle" was identified, whose diameter reached 200 m.

So how do "witches' circles" form, and why does lush green grass grow inside them and surround them on the outside?

This is because the mycelium grows radially, in a ring. The most vigorous part of the mycelium is in the peripheral part of the regular ring, in a 20–30 cm zone; here it is best developed and has accumulated the most nutrients, and here the primordia of the fruiting bodies form, from which only mushrooms grow, while grass is hardly to be seen. The dense mycelial tangle that develops in this zone (20–30 cm) uses up all the moisture, leaving none for the roots of the grasses, and a so-called physiological drought arises in the zone, which prevents grasses from growing. In addition, a high concentration of nitrogen and harmful substances secreted by the mycelium has been found in this zone, poisoning the grass roots, which is why they no longer grow.

The young, vigorous mycelium, using hydrolytic enzymes, breaks down the proteins and other organic substances in the soil beyond this mycelial zone and decomposes them into ammonia, which the bacteria present convert into nitrates easily absorbed by grasses; as a result the grass grows lushly and is a striking, deep green colour.

Inside the ring, when the old mycelium has died off and decomposed, many nitrogenous substances are also released; these are easily absorbed by herbaceous plants, which turn greener and lusher than those growing outside the rings. In this way the mycelium, having extracted during the growing season in its new location (the 20–30 cm zone) everything that was useful, necessary and accessible to it, and having grown a new generation of fruiting bodies, will keep spreading, again supply itself with essential food and again raise its offspring.

Mushrooms growing in rings no longer frighten mushroom pickers, but only delight them.