Marasmius rotula
Encyclopedia
Marasmius rotula is a species of fungus
in the Marasmiaceae
family of mushroom
s. It is commonly
known variously as the pinwheel mushroom, the pinwheel Marasmius, the little wheel, the collared parachute, or the horse hair fungus. It is a widespread and common fungus, and is the type species
of the genus Marasmius
. The fruit body
is characterized by its whitish, thin, membranous cap
, its long and slender but tough black stem
, and widely-spaced white gills that are attached to a collar encircling but not touching the stem. The fungus grows on decaying wood and leaves. Unlike other mushrooms known to release spores in response to an internal timer, or circadian rhythm
, spore release in M. rotula is dependent on rain.
as Agaricus rotula in 1772. In 1821 Elias Magnus Fries
redescribed the mushroom, and later sanctioned the name as Marasmius rotula in 1838. In 1946 Smith
and Singer
proposed to conserve the genus name Marasmius
over Micromphale, which had nomenclatorial priority, with M. rotula as the lectotype
. The genus Marasmius, with M. rotula as the lectotype species, was later conserved by the 1954 Paris Congress on Botanical Nomenclature.
It is commonly
known as the "pinwheel mushroom", the "pinwheel Marasmius", the "collared parachute", or the "horse hair fungus". The name "little wheel fungus" is suggestive of the collar to which the gills are attached like the spokes of a wheel. The specific epithet is derived from the Latin
word rota meaning "wheel".
of the fruit body
is thin and membranous, measuring 3 to 20 mm (0.118110236220472 to 0.78740157480315 in) in diameter. It has a convex shape, and is slightly depressed in the center. The cap color is whitish to light pinkish-white, slightly darker at the center, and smooth. The cap margin has scalloped edges and furrows that outline the shape of the gills on the underside; the radial furrows extend inward to one-third to three-quarters of the cap radius from the edge. The flesh
is thin and white.
The gills are attached to a collar, and are free from direct attachment to the stem, although some specimens may have the collar pressed close to the stem and this characteristic will be less obvious. The gills are whitish-pallid, widely-spaced; there are typically between 16 and 22 of them. The stem
is 2 to 5 cm (0.78740157480315 to 2 in) long and up to 0.1 cm (0.0393700787401575 in) thick, with a smooth, sometimes shiny surface. It is tough, hollow, slightly blackish-brown below, with a lighter apex that is almost translucent. The base of the stem may be connected to black root-like rhizomorphs. There is no partial veil
on the stem.
, the spores
of Marasmius rotula appear white or pale yellow. Viewed with a light microscope, the spores are hyaline
(translucent), teardrop or pip-shaped, and have dimensions of 7–10 by 3–5 µm
. The basidia (the spore-producing cells) are four-spored. Along the edge of the gill, interspersed among the basidia, are sterile (non-reproductive) cells called cystidia; they are club-shaped and have rough wart-like protuberances on the surface.
the heavy metal cadmium
; a study of the metal concentration of 15 wild Indian mushroom species showed that M. rotula had accumulated the highest concentration of cadmium.
like other typical agaric
and bolete
mushrooms, but rather, was dependent on rain. Like many other species of Marasmius, the fruit bodies of M. rotula can dry out in dry periods, and revive when sufficient moisture is available in the form of rain or high humidity
. In her study, fruit bodies were capable of discharging spores over a period of at least three weeks.
cap with a white center, and it grows on oak leaves, and is never clustered. Further, its cap is evenly rounded, unlike M. rotula, which is pleated and furrowed. Marasmius nigripes has white caps that are 5 to 10 mm (0.196850393700787 to 0.393700787401575 in), widely-spaced gills, and a dark stem covered with what appears to be a white powder. Mycena corticola is smaller than Marasmius rotula, has a pale pink-brown cap, and can is usually found growing singly or in groups on bark near the base of living trees. M. rotula is distinguished from M. bulliardi by its larger size, and greater number of gills.
The fungus is widespread and common in the British Isles, and has been collected in Shetland (Scotland), Nigeria, India, China, and Poland. In North America it is more commonly found in the east.
Fungus
A fungus is a member of a large group of eukaryotic organisms that includes microorganisms such as yeasts and molds , as well as the more familiar mushrooms. These organisms are classified as a kingdom, Fungi, which is separate from plants, animals, and bacteria...
in the Marasmiaceae
Marasmiaceae
The Marasmiaceae are a family of basidiomycete fungi which have white spores. They mostly have a tough stem and the capability of shrivelling up during a dry period and later recovering. The widely consumed edible fungus Lentinula edodes, the Shiitake mushroom, is a member of this family...
family of mushroom
Mushroom
A mushroom is the fleshy, spore-bearing fruiting body of a fungus, typically produced above ground on soil or on its food source. The standard for the name "mushroom" is the cultivated white button mushroom, Agaricus bisporus; hence the word "mushroom" is most often applied to those fungi that...
s. It is commonly
Common name
A common name of a taxon or organism is a name in general use within a community; it is often contrasted with the scientific name for the same organism...
known variously as the pinwheel mushroom, the pinwheel Marasmius, the little wheel, the collared parachute, or the horse hair fungus. It is a widespread and common fungus, and is the type species
Type species
In biological nomenclature, a type species is both a concept and a practical system which is used in the classification and nomenclature of animals and plants. The value of a "type species" lies in the fact that it makes clear what is meant by a particular genus name. A type species is the species...
of the genus Marasmius
Marasmius
Marasmius is a genus of mushrooms, in the family Marasmiaceae. It contains about 500 species of agarics, of which a few, such as Marasmius oreades, are edible. However, most members of this genus are small, unimpressive brown mushrooms...
. The fruit body
Ascocarp
An ascocarp, or ascoma , is the fruiting body of an ascomycete fungus. It consists of very tightly interwoven hyphae and may contain millions of asci, each of which typically contains eight ascospores...
is characterized by its whitish, thin, membranous cap
Pileus (mycology)
The pileus is the technical name for the cap, or cap-like part, of a basidiocarp or ascocarp that supports a spore-bearing surface, the hymenium. The hymenium may consist of lamellae, tubes, or teeth, on the underside of the pileus...
, its long and slender but tough black stem
Stipe (mycology)
thumb|150px|right|Diagram of a [[basidiomycete]] stipe with an [[annulus |annulus]] and [[volva |volva]]In mycology a stipe refers to the stem or stalk-like feature supporting the cap of a mushroom. Like all tissues of the mushroom other than the hymenium, the stipe is composed of sterile hyphal...
, and widely-spaced white gills that are attached to a collar encircling but not touching the stem. The fungus grows on decaying wood and leaves. Unlike other mushrooms known to release spores in response to an internal timer, or circadian rhythm
Circadian rhythm
A circadian rhythm, popularly referred to as body clock, is an endogenously driven , roughly 24-hour cycle in biochemical, physiological, or behavioural processes. Circadian rhythms have been widely observed in plants, animals, fungi and cyanobacteria...
, spore release in M. rotula is dependent on rain.
Taxonomy
The species was first named by Italian mycologist Giovanni Antonio ScopoliGiovanni Antonio Scopoli
Giovanni Antonio Scopoli was an Italian physician and naturalist.-Biography:...
as Agaricus rotula in 1772. In 1821 Elias Magnus Fries
Elias Magnus Fries
-External links:*, Authors of fungal names, Mushroom, the Journal of Wild Mushrooming.*...
redescribed the mushroom, and later sanctioned the name as Marasmius rotula in 1838. In 1946 Smith
Alexander H. Smith
Alexander Hanchett Smith was an American mycologist known for his extensive contributions to the taxonomy and phylogeny of the higher fungi, especially the agarics.-Early life:...
and Singer
Rolf Singer
Rolf Singer was a German-born mycologist and one of the most important taxonomists of gilled mushrooms in the 20th century....
proposed to conserve the genus name Marasmius
Marasmius
Marasmius is a genus of mushrooms, in the family Marasmiaceae. It contains about 500 species of agarics, of which a few, such as Marasmius oreades, are edible. However, most members of this genus are small, unimpressive brown mushrooms...
over Micromphale, which had nomenclatorial priority, with M. rotula as the lectotype
Lectotype
In botanical nomenclature and zoological nomenclature, a lectotype is a kind of name-bearing type. When a species was originally described on the basis of a name-bearing type consisting of multiple specimens, one of those may be designated as the lectotype...
. The genus Marasmius, with M. rotula as the lectotype species, was later conserved by the 1954 Paris Congress on Botanical Nomenclature.
It is commonly
Common name
A common name of a taxon or organism is a name in general use within a community; it is often contrasted with the scientific name for the same organism...
known as the "pinwheel mushroom", the "pinwheel Marasmius", the "collared parachute", or the "horse hair fungus". The name "little wheel fungus" is suggestive of the collar to which the gills are attached like the spokes of a wheel. The specific epithet is derived from the Latin
Latin
Latin is an Italic language originally spoken in Latium and Ancient Rome. It, along with most European languages, is a descendant of the ancient Proto-Indo-European language. Although it is considered a dead language, a number of scholars and members of the Christian clergy speak it fluently, and...
word rota meaning "wheel".
Description
The capPileus (mycology)
The pileus is the technical name for the cap, or cap-like part, of a basidiocarp or ascocarp that supports a spore-bearing surface, the hymenium. The hymenium may consist of lamellae, tubes, or teeth, on the underside of the pileus...
of the fruit body
Ascocarp
An ascocarp, or ascoma , is the fruiting body of an ascomycete fungus. It consists of very tightly interwoven hyphae and may contain millions of asci, each of which typically contains eight ascospores...
is thin and membranous, measuring 3 to 20 mm (0.118110236220472 to 0.78740157480315 in) in diameter. It has a convex shape, and is slightly depressed in the center. The cap color is whitish to light pinkish-white, slightly darker at the center, and smooth. The cap margin has scalloped edges and furrows that outline the shape of the gills on the underside; the radial furrows extend inward to one-third to three-quarters of the cap radius from the edge. The flesh
Trama (mycology)
In mycology trama is a term for the inner, fleshy portion of a mushroom's basidiocarp, or fruit body. It is distinct from the outer layer of tissue, known as the pileipellis or cuticle, and from the spore-bearing tissue layer known as the hymenium....
is thin and white.
The gills are attached to a collar, and are free from direct attachment to the stem, although some specimens may have the collar pressed close to the stem and this characteristic will be less obvious. The gills are whitish-pallid, widely-spaced; there are typically between 16 and 22 of them. The stem
Stipe (mycology)
thumb|150px|right|Diagram of a [[basidiomycete]] stipe with an [[annulus |annulus]] and [[volva |volva]]In mycology a stipe refers to the stem or stalk-like feature supporting the cap of a mushroom. Like all tissues of the mushroom other than the hymenium, the stipe is composed of sterile hyphal...
is 2 to 5 cm (0.78740157480315 to 2 in) long and up to 0.1 cm (0.0393700787401575 in) thick, with a smooth, sometimes shiny surface. It is tough, hollow, slightly blackish-brown below, with a lighter apex that is almost translucent. The base of the stem may be connected to black root-like rhizomorphs. There is no partial veil
Partial veil
thumb|150px|right|Developmental stages of [[Agaricus campestris]] showing the role and evolution of a partial veilPartial veil is a mycological term used to describe a temporary structure of tissue found on the fruiting bodies of some basidiomycete fungi, typically agarics...
on the stem.
Microscopic characteristics
Viewed in deposit, such as with a spore printSpore print
thumb|300px|right|Making a spore print of the mushroom Volvariella volvacea shown in composite: mushroom cap laid on white and dark paper; cap removed after 24 hours showing pinkish-tan spore print...
, the spores
Basidiospore
A basidiospore is a reproductive spore produced by Basidiomycete fungi. Basidiospores typically each contain one haploid nucleus that is the product of meiosis, and they are produced by specialized fungal cells called basidia. In grills under a cap of one common species in the phylum of...
of Marasmius rotula appear white or pale yellow. Viewed with a light microscope, the spores are hyaline
Hyaline
The term hyaline denotes a substance with a glass-like appearance.-Histopathology:In histopathological medical usage, a hyaline substance appears glassy and pink after being stained with haematoxylin and eosin — usually it is an acellular, proteinaceous material...
(translucent), teardrop or pip-shaped, and have dimensions of 7–10 by 3–5 µm
Micrometre
A micrometer , is by definition 1×10-6 of a meter .In plain English, it means one-millionth of a meter . Its unit symbol in the International System of Units is μm...
. The basidia (the spore-producing cells) are four-spored. Along the edge of the gill, interspersed among the basidia, are sterile (non-reproductive) cells called cystidia; they are club-shaped and have rough wart-like protuberances on the surface.
Edibility
Marasmius rotula is considered inedible, but not poisonous. The mushroom has no distinguishable odor, and the taste is mild or bitter. The fruit bodies have the ability to bioaccumulateBioaccumulation
Bioaccumulation refers to the accumulation of substances, such as pesticides, or other organic chemicals in an organism. Bioaccumulation occurs when an organism absorbs a toxic substance at a rate greater than that at which the substance is lost...
the heavy metal cadmium
Cadmium
Cadmium is a chemical element with the symbol Cd and atomic number 48. This soft, bluish-white metal is chemically similar to the two other stable metals in group 12, zinc and mercury. Similar to zinc, it prefers oxidation state +2 in most of its compounds and similar to mercury it shows a low...
; a study of the metal concentration of 15 wild Indian mushroom species showed that M. rotula had accumulated the highest concentration of cadmium.
Spore release
In 1975 American mycologist Martina S. Gilliam investigated the periodicity of spore release in M. rotula and concluded that spore discharge did not follow the regular circadian rhythmCircadian rhythm
A circadian rhythm, popularly referred to as body clock, is an endogenously driven , roughly 24-hour cycle in biochemical, physiological, or behavioural processes. Circadian rhythms have been widely observed in plants, animals, fungi and cyanobacteria...
like other typical agaric
Agaric
An agaric is a type of fungal fruiting body characterized by the presence of a pileus that is clearly differentiated from the stipe , with lamellae on the underside of the pileus. "Agaric" can also refer to a basidiomycete species characterized by an agaric-type fruiting body...
and bolete
Bolete
A bolete is a type of fungal fruiting body characterized by the presence of a pileus that is clearly differentiated from the stipe, with a spongy surface of pores on the underside of the pileus...
mushrooms, but rather, was dependent on rain. Like many other species of Marasmius, the fruit bodies of M. rotula can dry out in dry periods, and revive when sufficient moisture is available in the form of rain or high humidity
Humidity
Humidity is a term for the amount of water vapor in the air, and can refer to any one of several measurements of humidity. Formally, humid air is not "moist air" but a mixture of water vapor and other constituents of air, and humidity is defined in terms of the water content of this mixture,...
. In her study, fruit bodies were capable of discharging spores over a period of at least three weeks.
Similar species
Marasmius capillaris has a roughly similar appearance, but with a pale tanTan (color)
Tan is a pale whiteish, tawny shade of white. The name is derived from tannum used in the tanning of leather.The first recorded use of tan as a shade name in English was in the year 1590....
cap with a white center, and it grows on oak leaves, and is never clustered. Further, its cap is evenly rounded, unlike M. rotula, which is pleated and furrowed. Marasmius nigripes has white caps that are 5 to 10 mm (0.196850393700787 to 0.393700787401575 in), widely-spaced gills, and a dark stem covered with what appears to be a white powder. Mycena corticola is smaller than Marasmius rotula, has a pale pink-brown cap, and can is usually found growing singly or in groups on bark near the base of living trees. M. rotula is distinguished from M. bulliardi by its larger size, and greater number of gills.
Habitat and distribution
Marasmius rotula is a saprobic species, and obtains nutrients by decomposing dead organic matter. It grows on rotten leaves, dead wood (especially beech), or other woody debris in deciduous forests. The fruit bodies are easily overlooked because of their diminutive size.The fungus is widespread and common in the British Isles, and has been collected in Shetland (Scotland), Nigeria, India, China, and Poland. In North America it is more commonly found in the east.