''Marasmius oreades'', also known as the fairy ring mushroom or fairy ring champignon, is a mushroom native to North America and Europe. Its common names can cause some confusion, as many other mushrooms grow in

fairy ring A fairy ring, also known as fairy circle, elf circle, elf ring or pixie ring, is a naturally occurring ring or arc of mushrooms. They are found mainly in forested areas, but also appear in grasslands or rangelands. Fairy rings are detectable by ...

s, such as the edible ''

Agaricus campestris ''Agaricus campestris'' is a widely eaten gilled mushroom closely related to the cultivated button mushroom ''Agaricus bisporus''. It is commonly known as the field mushroom or, in North America, meadow mushroom. Taxonomy This species was ori ...

'' and the poisonous ''

Chlorophyllum molybdites ''Chlorophyllum molybdites,'' which has the common names of false parasol, green-spored Lepiota and vomiter, is a widespread mushroom. Poisonous and producing severe gastrointestinal symptoms of vomiting and diarrhea, it is commonly conflated wi ...

''.

Distribution and habitat

''Marasmius oreades'' grows extensively throughout North America, especially the east where they are also more diverse, and Europe in the summer and autumn (fall) (June–November in the UK), or year-round in warmer climates. It appears in grassy areas such as lawns, meadows, and even dunes in coastal areas.

Description

''Marasmius oreades'' grows gregariously in troops, arcs, or rings ( type II, which causes the grass to grow and become greener). The cap is across; bell-shaped with a somewhat inrolled margin at first, becoming broadly convex with an even or uplifted margin, but usually retaining a slight central bump- an " umbo"; dry; smooth; pale tan or buff, occasionally white, or reddish tan; usually changing color markedly as it dries out; the margin sometimes faintly lined.Marasmius oreades
(MushroomExpert.com) The bare, pallid, and tough stem grows up to about tall and in diameter. The gills are attached to the stem or free from it, fairly thick and spaced apart, and white or pale tan, with a

cyanide Cyanide is a naturally occurring, rapidly acting, toxic chemical that can exist in many different forms. In chemistry, a cyanide () is a chemical compound that contains a functional group. This group, known as the cyano group, consists of ...

-like odor and dropping a white

spore print 300px, Making a spore print of the mushroom ''Volvariella volvacea'' shown in composite: (photo lower half) mushroom cap laid on white and dark paper; (photo upper half) cap removed after 24 hours showing pinkish-tan spore print. A 3.5-centimeter ...

. The

spores In biology, a spore is a unit of sexual or asexual reproduction that may be adapted for dispersal and for survival, often for extended periods of time, in unfavourable conditions. Spores form part of the life cycles of many plants, algae, f ...

measure 7–10 μm × 4–6 μm; they are smooth, elliptical, and

inamyloid In mycology a tissue or feature is said to be amyloid if it has a positive amyloid reaction when subjected to a crude chemical test using iodine as an ingredient of either Melzer's reagent or Lugol's solution, producing a blue to blue-black stain ...

Cystidia A cystidium (plural cystidia) is a relatively large cell found on the sporocarp of a basidiomycete (for example, on the surface of a mushroom gill), often between clusters of basidia. Since cystidia have highly varied and distinct shapes that ar ...

absent.

Pileipellis The pileipellis is the uppermost layer of hyphae in the pileus of a fungal fruit body In botany, a fruit is the seed-bearing structure in flowering plants that is formed from the ovary after flowering. Fruits are the means by which flowe ...

without broom cells.

Edibility

''Marasmius oreades'' is a choice

edible mushroom Edible mushrooms are the fleshy and edible fruit bodies of several species of macrofungi (fungi which bear fruiting structures that are large enough to be seen with the naked eye). They can appear either below ground (hypogeous) or above ground ...

. Its sweet taste lends it to baked goods such as cookies. It is also used in foods such as soups, stews, etc. Traditionally, the stems (which tend to be fibrous and unappetizing) are cut off and the caps are threaded and dried in strings. A possible reason why this mushroom is so sweet-tasting is due to the presence of

trehalose Trehalose (from Turkish '' tıgala'' – a sugar derived from insect cocoons + -ose) is a sugar consisting of two molecules of glucose. It is also known as mycose or tremalose. Some bacteria, fungi, plants and invertebrate animals synthesize it ...

, a type of sugar that allows ''M. oreades'' to resist death by

desiccation Desiccation () is the state of extreme dryness, or the process of extreme drying. A desiccant is a hygroscopic (attracts and holds water) substance that induces or sustains such a state in its local vicinity in a moderately sealed container. ...

.Marasmius oreades, the fairy ring mushroom, leprechaun.
Tom Volk's Fungus of the Month for March 2003 When exposed to water after being completely dried out, the trehalose is digested as the cells completely revive, causing cellular processes, including the creation of new spores, to begin again.

Similar species

This mushroom can be mistaken for the toxic ''

Clitocybe dealbata ''Clitocybe dealbata'', also known as the ivory funnel, is a small white funnel-shaped toadstool widely found in lawns, meadows and other grassy areas in Europe and North America. Also known as the sweating mushroom, it derives this name from th ...

'' or '' C. rivulosa'', which have closely spaced decurrent gills. The latter lacks an umbo, and is white to grey in color. Some species of the '' Collybia'', ''

Marasmiellus ''Marasmiellus'' is a genus of fungi in the family Omphalotaceae (synonym to Marasmiaceae). The widespread genus, circumscribed by American mycologist William Murrill in 1915, contains over 250 species. The name comes from the Greek '' marasmus'' ...

'', '' Micromphale'', and '' Strobilurus'' genera are also similar, sometimes requiring microscopic analysis to differentiate.

References

External links

* {{Authority control Edible fungi Fungi found in fairy rings Fungi of Europe Fungi of North America Marasmius