They’re a curious sight: Perfectly round rings of mushrooms, growing that way all on their own. You might find them in forested areas, or you might find them on your lawn. You might even know what they’re called: “Fairy rings” —a seemingly magical name for a seemingly magical phenomenon.
But as for what fairy rings are, exactly? Unfortunately, they’re a good deal less magical than they appear. They’re just nature at work—the habit of some species of fungi to grow in a distinctive pattern based on a variety of biological factors. But although we know much about the inner workings of these curious-looking circles of mushrooms now, it took us a long time to get there. In the meantime, a vast amount of folklore sprang up around fairy rings in an attempt to explain everything from how they grow to what might happen if you interfere with one.
Here’s everything you had no idea you wanted to know about fairy rings—both from a scientific perspective and from a folkloric one.
The Science of Fairy Rings
Fairy rings, which typically show up in the warmer months (particularly in areas which see a lot of heavy rain during the spring and summer), begin with a single spore. The body of the fungus growing from this spore— what’s called the mycelium—takes up residence underground. As it continues to grow, though—that is, as it seeks out more nutrients to feed itself—it launches a whole bunch of threads stretching out from the original spore. As Eleanor Imster put it at EarthSky in 2015, it’s not unlike “spokes radiating from the hub of a wheel.”
The mushrooms visible above the ground put up from the edges of the mycelium—but, as Sarah Lamphier noted at the University of Notre Dame’s Center for STEM Education’s website in 2016, the organism is more than just that visible ring of fruiting bodies popping up on the Earth’s surface. It encompasses the full circle within the ring of mushrooms; we just can’t see it, because it lives mostly underground.
It’s worth noting, though, that there’s more than one kind of fairy ring. Yes, one consists solely of the visible circle of mushrooms for which the phenomenon is known. However, other varieties may manifest differently. For example, as a ring of mushrooms atop a circle of either dead grass or rapidly growing grass, or simply as a dark circle of grass with no mushrooms at all.
The fact that fairy rings can be responsible both for dead grass and for grass growing darker or out of control is interesting. Per the Missouri Botanical Garden, whether a fairy ring kills grass or grows it is determined by whether the fairy ring has accomplished one of two processes. Either the fungus’ mycelium has gotten particularly dense, thus preventing water from moving through the soil, or produces lots of hydrogen cyanide as a result of eating up all the nutrients in the soil, thereby killing the grass. It’s also possible the fungus has released a bunch of nitrogen after breaking down organic matter in the soil, which then causes the grass to grow rapidly and become dark green.
Somewhere in the neighborhood of 50 to 60 species of fungi can be responsible for the growth of a fairy ring. They’re typically of the Basidiomycota division, with common culprits including Agaricus campestris, also known as the field or meadow mushroom; Chlorophyllum molybdites, or the false parasol or green-spored Lepiota mushroom; and Marasmius oreades, known widely by its colloquial name, the Scotch bonnet mushroom. It’s crucial never, ever to eat mushrooms harvested from a fairy ring. However, some of the varieties that can be found in this formation are edible (the Scotch bonnet is, for instance), a huge number of them are poisonous. The false parasol, for example, is extremely poisonous, causing severe gastrointestinal issues within about three hours of consumption. (Not for nothing is one of its other nicknames “the vomiter.”)
In domesticated areas known for cultivated turf, fairy rings are viewed mainly as invasive, nuisances, or diseases. Golf courses, for example, consider them a particular scourge. However, as Scot Nelson pointed out in the article “Fairy Rings: Toadstools, Stinkhorns, and Puffballs,” published in the journal Plant Diseases in 2008, fairy rings have been around for much, much longer than nicely-manicured lawns have. Indeed, they might be some of the oldest living organisms in the world—possibly in the range of 600 to 700 years.
For the curious, the size of a fairy ring often indicates its age. Although your average fairy ring tends to be between two and 15 feet in diameter, one fairy ring located in Belfort, France, thought to be around 700 years old, is a whopping quarter-mile in diameter.
The Folklore of Fairy Rings
Because fairy rings have been around for so long, it’s no surprise that centuries of folklore surround their existence—including the origins of the name itself. “Fairy rings” were so called according to English and Celtic folklore because they were believed to have been caused by fairies or elves dancing together in a circle.
This belief dates back at least to the year 1300. Per The Meanings of Elf, and Elves, in Medieval England, written as a Ph. D. thesis by Dr. Alaric Hall, who is now a lecturer in medieval English literature at the University of Leeds, the first written instance of the Middle English word for “fairy ring” — “elferingewort,” which literally means “‘elf-ring-plant” —occurred at that time. Interestingly, the plant in question was not actually a fungus of any sort; it referred instead to a ring of daisies.
Whether daisies or mushrooms, though, fairy rings have long been believed to function as vortices of mysterious power. It’s not a power meant for humans, though; what’s abundantly clear according to nearly all of the tales is that humans should stay far, far away from fairy rings—and above all, that they should never consider even for a moment stepping inside one.
At best, humans who choose to dance with the fairies within their fairy rings will be compelled to do so until they collapse from exhaustion; then, once they’ve fallen unconscious, the fairies will toss their bodies about as if they were human beach balls. When the unfortunate humans awake the next morning, they’ll be found covered in bruises. (As Vivian Tower at the folklore-focused website Fairy Room notes, this particular story, which hails from the Normandy region of France, was recorded by Thomas Keightley in his book The Fairy Mythology, published in 1892. )
At worst, though, you might suffer something a bit more traumatic. You might, for example, find yourself cursed for stepping foot within a fairy ring, doomed to die within a year. You might find that, although only a few minutes have passed for you while you danced within the ring, time moved at a very different pace outside of it; years may have gone by while you have remained frozen in time. You might exit the fairy ring and find yourself unable to distinguish reality from fantasy—for the rest of your life. Or, you might never leave the ring at all: You might instead be whisked away to Fairyland, never to be seen again.
But the beliefs surrounding fairy rings vary from tradition to tradition—and they don’t always have anything to do with fairies. According to Dutch folklore, for example, these circles of mushrooms are said to be where the Devil rests his butter churn. Meanwhile, in Germany, the folklore paints them as places not where fairies dance, but where witches do—particularly on Walpurgisnacht, the spring festival celebrated at the end of April each year. A legend from the Tyrol region of Austria even states that the rings are the result of a dragon laying down its tail.
To be fair, some pieces of folklore position fairy rings as somewhat more positive. Per the Encyclopedia of Superstitions, Folklore, and the Occult Sciences of the World, originally published in 1903 and republished by University Press of the Pacific in 2003, a house built on a swathe of ground known to host fairy rings will bring prosperity to its inhabitants. The encyclopedia further notes that you can make visible the usually invisible world of the fairies if you “put your foot in a fairy-ring, with a companion’s foot on top of yours.” Still, though, you’d best make sure you put your coat on inside out before you give it a try. Doing so will protect from the fairies’ wrath.
But although different beliefs may cling to these strange circles of mushrooms growing in the grass, what nearly all of them have in common, as Vivian Tower writes at Fairy Room, is this: “A ring of toadstools marks off a space distinct from the human world.” Heck, that’s true even if you forego the folklore and look only at the science: No matter what humans might do to stop them, fairy rings persist in popping up time and time again.
That’s magical, no matter which way you look at it!