Fairy Rings
JB: This is Earth and Sky, with a question from a listener in Washington state.
DB: He writes, “I’ve noticed some mushrooms growing in circular patterns, sometimes several feet in diameter. Is there a name for this phenomenon? What causes it?”
JB: What you saw is known as a “fairy ring” – from the old belief that fairies danced inside the circle of mushrooms. Only a few kinds of mushrooms form fairy rings. You might’ve seen the mushroom called the Giant Puffball. Mushrooms are a type of fungus, and fairy rings form as a result of the way certain types of fungi grow.
DB: What happens is that these fungi start growing underground from a single spore. The spore sprouts a tangle of tube-like threads, which spread out horizontally in all directions – like spokes radiating from the hub of a wheel. That’s what gives rise to the circular pattern. The part of the fungus you see – the mushrooms – springs up at the edge of the circle.
JB: Scientists can measure the advance of a fungus from the increasing size of a fairy ring – so they can figure out when the ring started to grow. Some fairy rings have been found that may have been growing for four hundred years. To ask us your science question, come to earthsky.org. Special thanks today to the National Park Service, and to the National Fish and Wildlife Foundation – supporting the conservation of native fish, wildlife, plants and their habitats. We’re Block and Byrd for Earth and Sky.
The following people were interviewed for today’s program. Our thanks to:
Dr. Orson Miller
Professor of Botany / Curator of Fungi Virginia Polytechnic Institute and State College
Dr. Randy Molina
Forest Mycology
Team Leader
USDA Forest Service
If you enjoyed this program, you may be interested in the following websites:
Dr. Tom Volk’s Fungus Website (Dept of Botany, University of Wisconsin Madison)
For great pictures of Giant Puffball fairy rings (Dept of Botany, University of Wisconsin Madison)
Author’s notes:
You can sometimes see rings of mushrooms from the air as dark green circles surrounding patches of dead grass. As the fungus grows, it gradually decomposes the grass in its path. The dark green color of the fairy ring arises from the release of phosphorus and nitrogen from the most recently decomposed grass.
Additional Teacher Resources
U.S. National Service, North Cascade National Park: Nature & Science: Mushrooms and Other Fungi
This article explains the various types of mushroom and fungi found in the
North Cascade National Park and the greater Pacific Northwest. The article also discusses that like trees, fungi often grow in rings, which expand each year. The visible representation of this is what is called a “fairy ring.”
Colorado State University Cooperative Extension: Fairy Ring
This site presents a natural history of the processes of fairy rings. Included are sections specific to scientific introduction, how they are spread and develop how to manage them, and the historical significance of the process.
Cornell University, Plant Disease Diagnostic Clinic: Fairy Rings On Turfgrass: Various basidiomycetes
This site provides an introductory fact-sheet on fairy rings. It touches on the natural history of the fungi that creates the rings, the symptoms, the disease cycle, and the management of the rings.
