Pholiota squarrosa
Encyclopedia
Pholiota squarrosa, commonly known as the shaggy scalycap, the shaggy Pholiota, or the scaly Pholiota, is a species of mushroom
in the Strophariaceae
family. Common in North America and Europe, it is often an opportunistic parasite, and has a wide range of hosts
among deciduous
trees, although it can also infect conifers. It can also live as a saprobe, deriving nutrients from decomposing wood. The mushroom is typically found growing in clusters at the base of trees and stumps. Both the cap
and the stem
are covered in small, pointed scales that are pointed downward and backward. The crowded gills are yellowish, then later rust-brown. The mushroom has an odor that, depending on the author, has been described as resembling garlic, lemon, radish, onion, or skunk. It has a strong taste, resembling radishes. Once thought to be edible
, it is now considered and known to be poisonous, especially if consumed in combination with alcohol. The mushroom contains unique chemicals thought to help it infect plants by neutralizing defensive responses
employed by them. The very similar P. squarrosoides differs in having a paler cap that is sticky between the scales, and smaller spore
s.
as Agaricus squarrosus in 1790 by George Christian Edler von Oldenburg Oeder, and later sanctioned
under this name by Elias Magnus Fries
in his 1821 Systema Mycologicum
. It was transferred to the genus Pholiota
by the German Paul Kummer
. It is the type species
of the genus Pholiota.
The specific epithet squarrosa is derived from Latin
, and means "scurfy". The mushroom is commonly
known as the "scaly Pholiota", the "shaggy scalycap", or the "shaggy Pholiota".
and stem
. The cap ranges from 3 to 12 cm (1.2 to 4.7 in) in diameter, and depending on its age, can range in shape from bell-shaped to rounded to somewhat flattened. The cap color is yellowish-brown to tawny
in older specimens. The scales on the cap are yellowish to tawny, and recurved.
The stem is 4 to 12 cm (1.6 to 4.7 in) long by 0.5 to 1.5 cm (0.196850393700787 to 0.590551181102362 in) thick, and roughly equal in width throughout. The partial veil that covers the young gills forms a thick, woolly ring
on the upper part of the stem. Above the level of the ring, the stem is bare, while below it is scaly like the cap. The gills are covered by a partial veil
when young and have a greenish-brown color; mature gills are rusty brown. They are crowded closely together, attached to the stem (adnate), and usually notched (sinuate).
The spore print
is cinnamon or rusty brown. The spore
s are elliptic, smooth-walled, nonamyloid
(not absorbing iodine
when stained with Melzer's reagent
), and measure 6.6–8 by 3.7–4.4 μm
. The basidia (spore-bearing cells) are club-shaped, and four-spored, with dimensions of 16–25 by 5–7 μm.
, the mushroom has caused several cases of poisoning. The afflicted individuals had consumed alcohol with the mushroom, then experienced vomiting and diarrhea about ten hours later. The toxic effect may be due to the combination of eating the mushrooms and taking alcohol, although the extended time delay between consumption and symptoms suggests the mechanism of toxicity is different than the antabuse-effect experienced from Coprinopsis atramentaria
with alcohol.
can also be misidentified with P. squarrosa; it has white, adnexed gills with finely scalloped edges, but it can be distinguished most reliably by its white, nonamyloid
spores.
as a carbon source, and have the ability to degrade the lignin
(present in wood) to carbon dioxide
to access the cellulose molecule. The fungus can attack a wide variety of deciduous host
trees, including sugar maple
, red maple
, yellow birch
, paper birch
, American beech
, and white ash
. It can also attack conifers, like spruce
. The fungus is a secondary parasite, in that it attacks trees that have already been weakened from prior injury or infection by bacteria or other fungi. It also functions as a saprobe, and can obtain nutrients by breaking down organic matter in dead wood.
P. squarrosa is found in North America and Europe. The North American distribution extends north to Canada, and south to Mexico, where its appearance is restricted to coniferous forests. In the Netherlands, P. squarrosa is one of many mushrooms that can regularly be found fruiting on ancient timber wharves
.
The fruit bodies are used as a primary food source by the red squirrel Sciurus vulgaris, and have a higher protein content than the other mushrooms typically consumed by this species. Decaying fruit bodies are also used as a food source by fruit flies belonging to the genus Drosophila
.
s. The compounds, named squarrosidine and pinillidine, inhibit the enzyme xanthine oxidase
. Xanthine oxidase catalyzes the crystallization
of uric acid
in the joints, a main cause of gouty arthritis, and inhibitors of this enzyme are being used clinically to reduce this side effect. The natural function of these compounds may be to quench reactive oxygen species
produced by plants as a defensive response
to fungal infection.
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...
in the Strophariaceae
Strophariaceae
The Strophariaceae are a family of fungi in the order Agaricales. The family contains 18 genera and 1316 species. The species of Strophariaceae have a red-brown to dark brown spore print, while the spores themselves are smooth and have an apical germ pore. These agarics are also characterized by...
family. Common in North America and Europe, it is often an opportunistic parasite, and has a wide range of hosts
Host (biology)
In biology, a host is an organism that harbors a parasite, or a mutual or commensal symbiont, typically providing nourishment and shelter. In botany, a host plant is one that supplies food resources and substrate for certain insects or other fauna...
among deciduous
Deciduous
Deciduous means "falling off at maturity" or "tending to fall off", and is typically used in reference to trees or shrubs that lose their leaves seasonally, and to the shedding of other plant structures such as petals after flowering or fruit when ripe...
trees, although it can also infect conifers. It can also live as a saprobe, deriving nutrients from decomposing wood. The mushroom is typically found growing in clusters at the base of trees and stumps. Both the 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...
and 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...
are covered in small, pointed scales that are pointed downward and backward. The crowded gills are yellowish, then later rust-brown. The mushroom has an odor that, depending on the author, has been described as resembling garlic, lemon, radish, onion, or skunk. It has a strong taste, resembling radishes. Once thought to be edible
Edible mushroom
Edible mushrooms are the fleshy and edible fruiting bodies of several species of fungi. Mushrooms belong to the macrofungi, because their fruiting structures are large enough to be seen with the naked eye. They can appear either below ground or above ground where they may be picked by hand...
, it is now considered and known to be poisonous, especially if consumed in combination with alcohol. The mushroom contains unique chemicals thought to help it infect plants by neutralizing defensive responses
Hypersensitive response
The hypersensitive response is a mechanism, used by plants, to prevent the spread of infection by microbial pathogens. The HR is characterized by the rapid death of cells in the local region surrounding an infection. The HR serves to restrict the growth and spread of pathogens to other parts of...
employed by them. The very similar P. squarrosoides differs in having a paler cap that is sticky between the scales, and smaller spore
Spore
In biology, a spore is a reproductive structure that is adapted for dispersal and surviving for extended periods of time in unfavorable conditions. Spores form part of the life cycles of many bacteria, plants, algae, fungi and some protozoa. According to scientist Dr...
s.
Taxonomy
The species was first described scientificallySpecies description
A species description or type description is a formal description of a newly discovered species, usually in the form of a scientific paper. Its purpose is to give a clear description of a new species of organism and explain how it differs from species which have been described previously, or are...
as Agaricus squarrosus in 1790 by George Christian Edler von Oldenburg Oeder, and later sanctioned
Sanctioned name
In mycology, a sanctioned name is a name that was adopted in certain works of Christiaan Hendrik Persoon or Elias Magnus Fries, which are considered major points in fungal taxonomy.-Definition and effects:...
under this name by Elias Magnus Fries
Elias Magnus Fries
-External links:*, Authors of fungal names, Mushroom, the Journal of Wild Mushrooming.*...
in his 1821 Systema Mycologicum
Systema Mycologicum
Systema Mycologicum is a systematic classification of fungi drawn up in 1821 by the Swedish mycologist and botanist Elias Fries. It took 11 years to complete....
. It was transferred to the genus Pholiota
Pholiota
Pholiota is a genus of small to fleshy mushrooms in the family Strophariaceae. The genus has a widespread distribution, especially in temperate regions, and contains about 150 species....
by the German Paul Kummer
Paul Kummer
Paul Kummer was a priest, teacher, and scientist in Zerbst, Germany, known chiefly for his contribution to mycological nomenclature. Earlier classification of agarics by pioneering fungal taxonomist Elias Magnus Fries designated only a very small number of genera, with most species falling into...
. It 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 Pholiota.
The specific epithet squarrosa is derived from 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...
, and means "scurfy". The mushroom 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 "scaly Pholiota", the "shaggy scalycap", or the "shaggy Pholiota".
Description
Like other Pholiota mushrooms, P. squarrosa has a scaly 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...
and 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...
. The cap ranges from 3 to 12 cm (1.2 to 4.7 in) in diameter, and depending on its age, can range in shape from bell-shaped to rounded to somewhat flattened. The cap color is yellowish-brown to tawny
Tawny (color)
Tawny is a yellowish brown color. The word means "tan-colored," from Anglo-Norman tauné "associated with the brownish-yellow of tanned leather," from Old French tané "to tan hides," from Medieval Latin tannare, from tannum "crushed oak bark," used in tanning leather, probably from a Celtic source...
in older specimens. The scales on the cap are yellowish to tawny, and recurved.
The stem is 4 to 12 cm (1.6 to 4.7 in) long by 0.5 to 1.5 cm (0.196850393700787 to 0.590551181102362 in) thick, and roughly equal in width throughout. The partial veil that covers the young gills forms a thick, woolly ring
Annulus (mycology)
An annulus is the ring like structure sometimes found on the stipe of some species of mushrooms. The annulus represents the remaining part of the partial veil, after it has ruptured to expose the gills or other spore-producing surface. An annulus may be thick and membranous, or it may be cobweb-like...
on the upper part of the stem. Above the level of the ring, the stem is bare, while below it is scaly like the cap. The gills are covered by a 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...
when young and have a greenish-brown color; mature gills are rusty brown. They are crowded closely together, attached to the stem (adnate), and usually notched (sinuate).
The spore print
Spore 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...
is cinnamon or rusty brown. The spore
Spore
In biology, a spore is a reproductive structure that is adapted for dispersal and surviving for extended periods of time in unfavorable conditions. Spores form part of the life cycles of many bacteria, plants, algae, fungi and some protozoa. According to scientist Dr...
s are elliptic, smooth-walled, nonamyloid
Amyloid (mycology)
In mycology the term amyloid refers to a crude chemical test using iodine in either Melzer's reagent or Lugol's solution, to produce a black to blue-black positive reaction. It is called amyloid because starch gives a similar reaction, and that reaction for starch is also called an amyloid reaction...
(not absorbing iodine
Iodine
Iodine is a chemical element with the symbol I and atomic number 53. The name is pronounced , , or . The name is from the , meaning violet or purple, due to the color of elemental iodine vapor....
when stained with Melzer's reagent
Melzer's Reagent
Melzer's reagent is a chemical reagent used by mycologists to assist with the identification of fungi.-Composition:...
), and measure 6.6–8 by 3.7–4.4 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 (spore-bearing cells) are club-shaped, and four-spored, with dimensions of 16–25 by 5–7 μm.
Edibility
Fruit bodies have an odor described variously as resembling garlic, radish, lemon, onion, or skunk, and taste like radish. Although some older sources report P. squarrosa as edibleEdible mushroom
Edible mushrooms are the fleshy and edible fruiting bodies of several species of fungi. Mushrooms belong to the macrofungi, because their fruiting structures are large enough to be seen with the naked eye. They can appear either below ground or above ground where they may be picked by hand...
, the mushroom has caused several cases of poisoning. The afflicted individuals had consumed alcohol with the mushroom, then experienced vomiting and diarrhea about ten hours later. The toxic effect may be due to the combination of eating the mushrooms and taking alcohol, although the extended time delay between consumption and symptoms suggests the mechanism of toxicity is different than the antabuse-effect experienced from Coprinopsis atramentaria
Coprinopsis atramentaria
Coprinopsis atramentaria, commonly known as the common ink cap or inky cap, is an edible mushroom found in Europe and North America. Previously known as Coprinus atramentarius, it is the second best known ink cap and previous member of the genus Coprinus after C. comatus...
with alcohol.
Similar species
Pholiota squarrosa is similar in appearance to species in the genus Armillaria, but the latter produces white spore prints. Another similar mushroom is Pholiota squarrosoides, which can be distinguished microscopically by its smaller spores, and macroscopically by the stickiness of the cap between the scales. P. squarrosoides also lacks the odor of P. squarrosa, and has flesh that is white, not yellow. Leucopholiota decorosaLeucopholiota decorosa
Leucopholiota decorosa is a species of fungus in the Tricholomataceae family of mushrooms. Commonly known as the decorated Pholiota, it is distinguished by its fruit body which is covered with pointed brown, curved scales on the cap and stem, and by its white gills...
can also be misidentified with P. squarrosa; it has white, adnexed gills with finely scalloped edges, but it can be distinguished most reliably by its white, nonamyloid
Amyloid (mycology)
In mycology the term amyloid refers to a crude chemical test using iodine in either Melzer's reagent or Lugol's solution, to produce a black to blue-black positive reaction. It is called amyloid because starch gives a similar reaction, and that reaction for starch is also called an amyloid reaction...
spores.
Ecology, habitat and distribution
Pholiota squarrosa is thought to be a white rot fungus, which use celluloseCellulose
Cellulose is an organic compound with the formula , a polysaccharide consisting of a linear chain of several hundred to over ten thousand β linked D-glucose units....
as a carbon source, and have the ability to degrade the lignin
Lignin
Lignin or lignen is a complex chemical compound most commonly derived from wood, and an integral part of the secondary cell walls of plants and some algae. The term was introduced in 1819 by de Candolle and is derived from the Latin word lignum, meaning wood...
(present in wood) to carbon dioxide
Carbon dioxide
Carbon dioxide is a naturally occurring chemical compound composed of two oxygen atoms covalently bonded to a single carbon atom...
to access the cellulose molecule. The fungus can attack a wide variety of deciduous host
Host (biology)
In biology, a host is an organism that harbors a parasite, or a mutual or commensal symbiont, typically providing nourishment and shelter. In botany, a host plant is one that supplies food resources and substrate for certain insects or other fauna...
trees, including sugar maple
Sugar Maple
Acer saccharum is a species of maple native to the hardwood forests of northeastern North America, from Nova Scotia west to southern Ontario, and south to Georgia and Texas...
, red maple
Red Maple
Acer rubrum , is one of the most common and widespread deciduous trees of eastern North America. It ranges from the Lake of the Woods on the border between Ontario and Minnesota, east to Newfoundland, south to near Miami, Florida, and southwest to east Texas...
, yellow birch
Yellow Birch
Betula alleghaniensis , is a species of birch native to eastern North America, from Newfoundland to Nova Scotia, New Brunswick, southern Quebec and Ontario, and the southeast corner of Manitoba in Canada, west to Minnesota, and south in the Appalachian Mountains to northern Georgia.It is a...
, paper birch
Paper Birch
Betula papyrifera is a species of birch native to northern North America.-Description:...
, American beech
American Beech
Fagus grandifolia, also known as American Beech or North american beech, is a species of beech native to eastern North America, from Nova Scotia west to southern Ontario in southeastern Canada, west to Wisconsin and south to eastern Texas and northern Florida in the United States. Trees in the...
, and white ash
White Ash
For another species referred to as white ash, see Eucalyptus fraxinoides.Fraxinus americana is a species of Fraxinus native to eastern North America found in mesophytic hardwood forests from Nova Scotia west to Minnesota, south to northern Florida, and southwest to eastern...
. It can also attack conifers, like spruce
Spruce
A spruce is a tree of the genus Picea , a genus of about 35 species of coniferous evergreen trees in the Family Pinaceae, found in the northern temperate and boreal regions of the earth. Spruces are large trees, from tall when mature, and can be distinguished by their whorled branches and conical...
. The fungus is a secondary parasite, in that it attacks trees that have already been weakened from prior injury or infection by bacteria or other fungi. It also functions as a saprobe, and can obtain nutrients by breaking down organic matter in dead wood.
P. squarrosa is found in North America and Europe. The North American distribution extends north to Canada, and south to Mexico, where its appearance is restricted to coniferous forests. In the Netherlands, P. squarrosa is one of many mushrooms that can regularly be found fruiting on ancient timber wharves
Wharf
A wharf or quay is a structure on the shore of a harbor where ships may dock to load and unload cargo or passengers.Such a structure includes one or more berths , and may also include piers, warehouses, or other facilities necessary for handling the ships.A wharf commonly comprises a fixed...
.
The fruit bodies are used as a primary food source by the red squirrel Sciurus vulgaris, and have a higher protein content than the other mushrooms typically consumed by this species. Decaying fruit bodies are also used as a food source by fruit flies belonging to the genus Drosophila
Drosophila
Drosophila is a genus of small flies, belonging to the family Drosophilidae, whose members are often called "fruit flies" or more appropriately pomace flies, vinegar flies, or wine flies, a reference to the characteristic of many species to linger around overripe or rotting fruit...
.
Chemistry
The fruit bodies contain unique chemical compounds that are derived from phenylpropanoidPhenylpropanoid
The phenylpropanoids are a diverse family of organic compounds that are synthesized by plants from the amino acid phenylalanine. Their name is derived from the six-carbon, aromatic phenyl group and the three-carbon propene tail of cinnamic acid, which is synthesized from phenylalanine in the first...
s. The compounds, named squarrosidine and pinillidine, inhibit the enzyme xanthine oxidase
Xanthine oxidase
Xanthine oxidase Xanthine oxidase Xanthine oxidase (XO (sometimes 'XAO'), a form of xanthine oxidoreductase that generates reactive oxygen species. Is an enzyme that catalyzes the oxidation of hypoxanthine to xanthine and can further catalyze the oxidation of xanthine to uric acid...
. Xanthine oxidase catalyzes the crystallization
Crystallization
Crystallization is the process of formation of solid crystals precipitating from a solution, melt or more rarely deposited directly from a gas. Crystallization is also a chemical solid–liquid separation technique, in which mass transfer of a solute from the liquid solution to a pure solid...
of uric acid
Uric acid
Uric acid is a heterocyclic compound of carbon, nitrogen, oxygen, and hydrogen with the formula C5H4N4O3. It forms ions and salts known as urates and acid urates such as ammonium acid urate. Uric acid is created when the body breaks down purine nucleotides. High blood concentrations of uric acid...
in the joints, a main cause of gouty arthritis, and inhibitors of this enzyme are being used clinically to reduce this side effect. The natural function of these compounds may be to quench reactive oxygen species
Reactive oxygen species
Reactive oxygen species are chemically reactive molecules containing oxygen. Examples include oxygen ions and peroxides. Reactive oxygen species are highly reactive due to the presence of unpaired valence shell electrons....
produced by plants as a defensive response
Hypersensitive response
The hypersensitive response is a mechanism, used by plants, to prevent the spread of infection by microbial pathogens. The HR is characterized by the rapid death of cells in the local region surrounding an infection. The HR serves to restrict the growth and spread of pathogens to other parts of...
to fungal infection.