Etymology of Maramius oreades

Marasmius: The name of the genus originates from the ancient Greek word “marasmus” which means “drying out”. Indeed, the mushrooms of this genus dry easily, be it on a sunny window sill or in the field, and can return to their original condition when rehydrated. This is thanks to a high concentration trehalose, a type of sugar, that protects the cell walls of the mushroom when desiccated. Amazingly, the mushroom actually comes back to life, conducting cellular respiration, spore release, and cell division when rehydrated. 

Oreades: The specific epithet comes from the “oread” of Greek mythology. Oreades were considered forest/mountain nymphs, or nature spirits, who had magical powers and promoted fertility in nature. The reason this name was chosen by James Bolton in the late 1700s was likely due to the seemingly magical growth of these mushrooms that can occur in perfect rings. As the name suggests, this formation has been associated with mystic spirits

Why Is It Called Fairy Ring Mushroom?

Few mushrooms have a name as imaginative as the Fairy Ring Mushroom. They are also sometimes known more specifically as Fairy Ring Marasmius. This mushroom owes its name thanks to its habit of growing in near-perfect circles that can be up to a meter in diameter. In European folklore, these circles were often associated with spirits and magical creatures such as fairies. Some legends suggest that these rings occur where these mystic spirits were dancing the day before. Other stories say it is bad luck or even dangerous to step inside these fairy rings. 

Today, the formation of Fairy Rings is known to occur because of a natural phenomenon. Essentially, when a spore germinates on a generally homogenous substrate, it grows in a circular form. This is the same as happens when scientists cultivate fungi in petri dishes. Once the mycellium has gathered enough nutrients and the weather conditions are right, the mushrooms are produced by the fungi at the perimeter of its mycellium. In some cases, the inside of the Fairy Rings are greener as the soils have more available nutrients due to the decomposition by the fungus. 

Also, just note that Fairy Ring Mushrooms aren’t the only species that grow in these rings. Many other species can do this, including various toxic ones. Lastly, Fairy Ring Mushrooms can also grow in lines and other non-circular shapes.