Marasmius oreades

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by Michael Kuo

This mushroom is often called the "Fairy Ring Mushroom," since it frequently fruits in rings on lawns, in meadows, and in other grassy places. Many other mushrooms create Fairy Rings, however, and if the e-mails I often receive are any indication, the use of the common name "Fairy Ring Mushroom" for Marasmius oreades leads to substantial confusion, causing Chlorophyllum molybdites, Agaricus campestris, and other mushrooms to be mislabeled.

Besides, the ring created by Marasmius oreades is often indistinct, and can't always serve as a way to identify the mushroom. It is best recognized with a combination of features:

• Habitat in grass.
• Well-spaced, white or buff gills that are attached to the stem but do not run down it.
• White spore print.
• Pale tan caps that are broadly bell-shaped or have a central bump.
• Tough, pliant stem.

Many mycophagists (the pretentious word for "mushroom eaters") are fond of Marasmius oreades. It is a popular edible worldwide, but I haven't tried it. Most authors recommend discarding the tough stems. According to some authors, Marasmius oreades affects some people adversely--so use caution if you are trying it for the first time.

Description:

Ecology: Saprobic on grass in lawns, meadows, and other grassy areas; frequently growing among coastal grasses in dunes; growing gregariously in troops, arcs, or rings; summer and fall--or year-round in warmer climates; widely distributed in North America.

Cap: 1-5 cm across; bell-shaped with a somewhat inrolled margin at first, becoming broadly convex with an even or uplifted margin, but often retaining a slight central bump; dry; smooth; pale tan or buff--occasionally white, or reddish tan; usually changing color markedly as it dries out; the margin sometimes faintly lined.

Gills: Attached to the stem or free from it; nearly distant; white or pale tan.

Stem: 2-8 cm long; 1.5-6 mm thick; equal; dry; tough and pliant; whitish or colored like the cap.

Flesh: Tough; whitish.

Taste: Mild; odor mild.

Spore Print: White.

Microscopic Features: Spores 7-10 x 4-6 µ; smooth; elliptical; inamyloid. Cystidia absent. Pileipellis without broom cells.

REFERENCES: (Bolton, 1792) Fries, 1836. (Gilliam, 1976; Smith, Smith & Weber, 1979; Weber & Smith, 1985; Arora, 1986; Phillips, 1991/2005; Lincoff, 1992; Horn, Kay & Abel, 1993; Evenson, 1997; Barron, 1999; Roody, 2003; Murphy, 2005; McNeil, 2006; Kuo, 2007.) Herb. Kuo 08170309, 08080501.

Further Online Information:

Marasmius oreades at Tom Volk's Fungi
Marasmius oreades at MykoWeb
Marasmius oreades at Roger's Mushrooms
Marasmius oreades at Fungi of Poland
Marasmius oreades at Mapping Macromycetes in Norway

A Marasmius oreades Fairy Ring, without the mushrooms. The growing mycelium causes the grass to be darker.

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Cite this page as:

Kuo, M. (2004, November). Marasmius oreades. Retrieved from the MushroomExpert.Com Web site: http://www.mushroomexpert.com/marasmius_oreades.html