Pholiota squarrosa

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Pholiota squarrosa
Sparrige-Schuppling (Pholiota squarrosa).JPG
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Fungi
Division: Basidiomycota
Class: Agaricomycetes
Order: Agaricales
Family: Strophariaceae
Genus: Pholiota
Species:
P. squarrosa
Binomial name
Pholiota squarrosa
(Oeder) Kumm. (1871)
Synonyms [1]
  • Agaricus squarrosusOeder (1770)
Pholiota squarrosa
Information icon.svg
Gills icon.png Gills on hymenium
Convex cap icon.svgFlat cap icon.svg Cap is convex or flat
Adnate gills icon2.svgSinuate gills icon2.svg Hymenium is adnate or sinuate
Ring stipe icon.svg Stipe has a ring
Transparent spore print icon.svg
Spore print is brown
Parasitic fungus.svgEcology is parasitic
Mycomorphbox Caution.pngEdibility is not recommended

Pholiota squarrosa, commonly known as the shaggy scalycap, the shaggy Pholiota, or the scaly Pholiota, is a species of mushroom in the family Strophariaceae. Common in North America and Europe, it 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 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.

Contents

The mushroom is typically found growing in clusters at the base of trees and stumps. [2] 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. Though edible to some, it may be toxic, 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 spores.

Taxonomy

The species was first described scientifically as Agaricus squarrosus in 1790 by Georg Christian Oeder, and later sanctioned under this name by Elias Magnus Fries in his 1821 Systema Mycologicum . [3] It was transferred to the genus Pholiota by the German Paul Kummer. [4] It is the type species of the genus Pholiota. [5]

The specific epithet squarrosa is derived from Latin, and means "scurfy". [6] The mushroom is commonly known as the "scaly Pholiota", [7] the "shaggy scalycap", [8] or the "shaggy Pholiota". [9]

Description

View of gills and stems Pholiota squarrosa JPG2.jpg
View of gills and stems

Like other Pholiota mushrooms, P. squarrosa has a scaly cap 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. [10] [11]

The stem is 4 to 12 cm (1.6 to 4.7 in) long by 0.5 to 1.5 cm (0.20 to 0.59 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). [10] [11]

The spore print is cinnamon or rusty brown. The spores 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. [7]

Fruit bodies have an odour described variously as resembling garlic, [7] radish, lemon, onion, or skunk, [6] and taste like radish. [12]

Edibility

Although some sources report P. squarrosa as edible, [13] the mushroom has caused several cases of poisoning. The afflicted individuals had consumed alcohol with the mushroom, then experienced vomiting and diarrhoea about ten hours later. [14] 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. [7]

Similar species

Leucopholiota decorosa is a lookalike. Leucopholiota decorosa 24649.jpg
Leucopholiota decorosa is a lookalike.

Pholiota squarrosa is similar in appearance to species in the genus Armillaria , but the latter produces white spore prints. [15] 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. [11] P. squarrosoides also lacks the odor of P. squarrosa, and has flesh that is white, not yellow. [16] Leucopholiota decorosa 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. [17]

Other similar species include Pholiota aurivella , P. populnea, and P. terrestris. [13]

Ecology, habitat and distribution

Pholiota squarrosa is thought to be a white rot fungus, which use cellulose 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. [18] It also functions as a saprobe, and can obtain nutrients by breaking down organic matter in dead wood. [19]

P. squarrosa is found in North America and Europe. [15] The North American distribution extends north to Canada, [6] and south to Mexico, where its appearance is restricted to coniferous forests. [20] In the Netherlands, P. squarrosa is one of many mushrooms that can regularly be found fruiting on ancient timber wharves. [21]

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. [22] Decaying fruit bodies are also used as a food source by fruit flies of the genus Drosophila . [23]

Chemistry

The fruit bodies contain unique chemical compounds that are derived from phenylpropanoids. 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. [24]

See also

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<i>Psilocybe pelliculosa</i> Species of fungus

Psilocybe pelliculosa is a species of fungus in the family Hymenogastraceae. The fruit bodies, or mushrooms, have a conical brownish cap up to 2 cm in diameter atop a slender stem up to 8 cm long. It has a white partial veil that does not leave a ring on the stem. American mycologist Alexander H. Smith first described the species in 1937 as a member of the genus known today as Psathyrella; it was transferred to Psilocybe by Rolf Singer in 1958.

<i>Volvariella bombycina</i> Species of mushroom in the family Pluteaceae

Volvariella bombycina, commonly known as the silky sheath, silky rosegill, silver-silk straw mushroom, or tree mushroom, is a species of edible mushroom in the family Pluteaceae. It is an uncommon but widespread species, having been reported from Asia, Australia, the Caribbean, Europe, and North America. The fruit body (mushroom) begins developing in a thin, egg-like sac. This ruptures and the stem expands quickly, leaving the sac at the base of the stem as a volva. The cap, which can attain a diameter of up to 20 centimetres, is white to slightly yellowish and covered with silky hairs. On the underside of the cap are closely spaced gills, free from attachment to the stem, and initially white before turning pink as the spores mature. The mushroom grows singly or in clusters, often appearing in old knotholes and wounds in elms and maples. V. bombycina contains compounds with antibacterial properties.

<i>Pholiota nubigena</i> Species of fungus

Pholiota nubigena, commonly known as the gastroid pholiota or the bubble gum fungus, is a species of secotioid fungus in the family Strophariaceae. It is found in mountainous areas of the western United States, where it grows on rotting conifer wood, often fir logs. It fruits in spring, often under snow, and early summer toward the end of the snowmelt period in high mountain forests. Fruit bodies appear similar to unopened mushrooms, measuring 1–4 centimetres tall with 1–2.4 cm diameter caps that are whitish to brownish. They have a short but distinct whitish stipe that extend through the internal spore mass (gleba) of the fruit body into the cap. The gleba consists of irregular chambers made of contorted gills that are brownish in color. A whitish, cottony partial veil is present in young specimens, but it often disappears in age and does not leave a ring on the stipe.

<i>Pholiota gummosa</i> Species of fungus

Pholiota gummosa, commonly known as the sticky scalycap, is a common species of mushroom-forming fungus in the family Strophariaceae. It is found in Europe and North America, where it grows as a saprotroph on the rotting wood of deciduous trees, including trunks and roots. It can also grow on wood buried near the surface, making it seem as if it is fruiting in grass.

<i>Pholiota squarrosoides</i> Species of fungus

Pholiota squarrosoides is a species of mushroom in the family Strophariaceae. It is similar to the species Pholiota squarrosa. There are differing accounts on whether the mushroom is edible.

References

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