Tylopilus plumbeoviolaceus
Encyclopedia
Tylopilus plumbeoviolaceus (formerly Boletus plumbeoviolaceus), commonly
known as the violet-grey bolete, is a fungus
of the bolete family
. First described in 1936, the mushroom has a disjunct distribution
, and is distributed in eastern North America and Korea. The fruit bodies
of the fungus are violet when young, but fade into a chocolate brown color when mature. They are solid and relatively large—cap
diameter up to 15 cm (5.9 in), with a white pore surface that later turns pink, and a white mycelium
at the base of the stem
. Like most bolete
s of genus Tylopilus
, the mushroom is inedible due to its bitter taste. A number of natural products have been identified from the fruit bodies, including unique chemical derivatives of ergosterol
, a fungal sterol
.
and one of his graduate students, Esther A. Dick, based on specimens found in the Black Rock Forest
near Cornwall, New York
. Regarding his decision to use the taxonomic rank forma, Snell wrote:
size, were enough to justify it being a species distinct from B. felleus, so in 1941 they raised the taxon
to species status with the name Boletus plumbeoviolaceus. Noted Agaricales
taxonomist Rolf Singer
later transferred the taxon
to Tylopilus
in 1947, a genus characterized by a spore print
that is pink, or purplish (vinaceous), rather than brown as in Boletus.
The specific name "plumbeoviolaceus" is coined from the Latin
adjectives plumbeus ("leaden" or "lead-colored") and violaceus ("purple"). The mushroom is commonly
known as the "violet-grey bolete".
of the fruit body
is 7 to 15 cm (2.8 to 5.9 in) in diameter, initially convex in shape but becoming centrally depressed, with a broadly arched and rounded margin. Young specimens are rather hard and firm, and the cap has a finely velvet-textured surface that soon wears off to become smooth. The color of the fruit body is violet when young, but dulls as it ages, becoming a dull violet-purplish-gray, then eventually chocolate-brown at maturity. The flesh
is solid, white, and does not change color when cut or bruised. The taste is bitter, and the odor is not distinctive. Mycologist David Arora
calls the mushroom "beautiful, but bitter-tasting".
The tubes on the underside of the cap are 0.4 to 1.8 cm (0.15748031496063 to 0.708661417322835 in) deep, 2 or three per millimeter, depressed at the stem (resulting in an adnate attachment). The color of the pore surface is initially white, and it remains so for a while before turning a rosy color at maturity. The stem
is 8 to 13 cm (3.1 to 5.1 in) long and 2.5 to 4 cm (0.984251968503937 to 1.6 in) thick, enlarged at the base, and sometimes bulbous. The surface is slightly reticulate at the top, and smooth lower of the stem. Its color is buff to light brown, often with darker brown bruises or stains, and it has whitish mycelium
at the base. The flesh of the stem is white, and it does not change color when cut or bruised.
, the spores of T. plumbeoviolaceus appear to be a light pink to flesh color. When viewed with a light microscope, they are elliptical, with smooth walls and dimensions of 9.1–12.3 by 3.4–4.5 µm
. The basidia (cellular structures that produce the spores) are club-shaped, and measure about 26 by 6.5 µm. The cuticle of the cap (the pileipellis
) is made of a tangle of smooth-walled, narrow, brownish hyphae. When stained in potassium hydroxide
, the hyphal contents tend to form beads, while staining in Melzer's reagent
causes the pigment to form globules. Cystidia are common in the hymenial
tissue; they are swollen at the base and narrow at the apex (lageniform), measuring 30–40 µm long by 7–9 µm thick. Clamp connection
s are absent in the hypha
e.
, has an appearance similar to T. plumbeoviolaceus. It can be distinguished by a paler, lilac-colored cap that, in older specimens, is discolored rusty purple along the edge of the cap. Its spores are 7–10 by 3–4 µm. Tylopilus violatinctus was not described until 1998, so some older literature may confuse the two similar species.
Young specimens of Tylopilus rubrobrunneus have a purplish cap, but unlike T. plumbeoviolaceous, their stems are never purple. The species Tylopilus microsporus, known only from China, is characterized by pale violet to violet cap, paler purple to purplish brown stem, and flesh color to pale purplish red pores. In addition to its different distribution, it can be distinguished from T. plumbeoviolaceus by its smaller spores. Another similar Asian species, T. obscureviolaceus, is only known from the Yaeyama Islands
in southwestern Japan. It differs from T. plumbeoviolaceous in having a cap that does not fade in color to grayish or brownish when mature, shorter spores (6–7.2 by 3.3–4 µm), and other microscopic characteristics.
l species, and the bulk of the fungus lives underground, associating in a mutualistic relationship with the roots of various tree species. The fruit bodies are found growing singly, scattered or clustered together during mid-summer to autumn in deciduous forests, often under beech
or oak
trees; however, it sometimes occurs in mixed hardwood-conifer forests under hemlock
. A preference for sandy soil has been noted in one source. In North America, the mushroom can be found east of the Rocky Mountains
, ranging from Canada to Mexico. The species has also been collected in North Korea
. Fruit bodies can serve as a food source for fungus-feeding Drosophila
flies.
of ergosterol
have been isolated from the fruit bodies of T. plumbeoviolaceus: tylopiol A (3β-hydroxy-8α,9α-oxido-8,9-secoergosta-7,9(11),22-triene) and tylopiol B (3β-hydroxy-8α,9α-oxido-8,9-secoergosta-7,22dien-12-one). These sterols are unique to this species. Additionally, the compounds ergosta-7,22-dien-3β-ol, uridine
, allitol, ergosterol, ergosterol 5α,8α-peroside, ergothioneine
, adenosine, and uracil
have been identified from the mushrooms.
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 violet-grey bolete, is a fungus
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...
of the bolete family
Boletaceae
Boletaceae are a family of mushrooms, primarily characterized by developing their spores in small pores on the underside of the mushroom, instead of gills, as are found in agarics. Nearly as widely distributed as agarics, they include the Cep or King Bolete , much sought after by mushroom hunters...
. First described in 1936, the mushroom has a disjunct distribution
Disjunct distribution
In biology, a taxon with a disjunct distribution is one that has two or more groups that are related but widely separated from each other geographically...
, and is distributed in eastern North America and Korea. The fruit bodies
Basidiocarp
In fungi, a basidiocarp, basidiome or basidioma , is the sporocarp of a basidiomycete, the multicellular structure on which the spore-producing hymenium is borne. Basidiocarps are characteristic of the hymenomycetes; rusts and smuts do not produce such structures...
of the fungus are violet when young, but fade into a chocolate brown color when mature. They are solid and relatively large—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...
diameter up to 15 cm (5.9 in), with a white pore surface that later turns pink, and a white mycelium
Mycelium
thumb|right|Fungal myceliaMycelium is the vegetative part of a fungus, consisting of a mass of branching, thread-like hyphae. The mass of hyphae is sometimes called shiro, especially within the fairy ring fungi. Fungal colonies composed of mycelia are found in soil and on or within many other...
at the base of 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...
. Like most 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...
s of genus Tylopilus
Tylopilus
Tylopilus is a large genus of around 75 species of mycorrhizal bolete fungi separated from Boletus. Its best known member is the bitter bolete , the only species found in Europe. More species are found in North America, such as the edible species Tylopilus chromapes and T. alboater, and the...
, the mushroom is inedible due to its bitter taste. A number of natural products have been identified from the fruit bodies, including unique chemical derivatives of ergosterol
Ergosterol
Ergosterol is a sterol found in fungi, and named for ergot, a common name for the members of the fungal genus Claviceps from which ergosterol was first isolated. Ergosterol does not occur in plant or animal cells...
, a fungal sterol
Sterol
Sterols, also known as steroid alcohols, are a subgroup of the steroids and an important class of organic molecules. They occur naturally in plants, animals, and fungi, with the most familiar type of animal sterol being cholesterol...
.
Taxonomy
The species was first named 1936 as Boletus felleus forma plumbeoviolaceus by American mycologist Walter H. SnellWally Snell
Walter Henry "Doc" Snell was a pinch-hitter/catcher in Major League Baseball who played briefly for the Boston Red Sox during the season. Following this brief baseball career he became a successful mycologist who worked primarily at Brown University for the next 60 years.-Baseball career:Snell...
and one of his graduate students, Esther A. Dick, based on specimens found in the Black Rock Forest
Black Rock Forest
Black Rock Forest is a privately owned nature preserve in the western Hudson Highlands region of the U.S. state of New York. It is in Orange County, mostly in the town of Cornwall, with the southern fringe overlapping into the neighboring town of Highlands...
near Cornwall, New York
Cornwall, New York
Cornwall is a town in Orange County, New York, USA. It is located about 50 miles north of New York City on the western shore of the Hudson River. The estimated population in 2007 was 12,827....
. Regarding his decision to use the taxonomic rank forma, Snell wrote:
"The writer hesitates to multiply the number of forms (formae) and varieties with distinctive names, because of the ease with which one develops the habit of interpreting slight variations as definite taxonomic units... the word "form" is used instead of "variety" as making no commitment as to the actual status of the variable segregate under consideration, until further information is available."The first collections made of the mushroom were of young, immature specimens, from which authors were unable to obtain spores for examination. It was not until a few years after that they found mature fruit bodies, which revealed that the rosy color of the pore surface took some time to develop. They concluded that this and other differences in physical characteristics, as well as differences in 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...
size, were enough to justify it being a species distinct from B. felleus, so in 1941 they raised the taxon
Taxon
|thumb|270px|[[African elephants]] form a widely-accepted taxon, the [[genus]] LoxodontaA taxon is a group of organisms, which a taxonomist adjudges to be a unit. Usually a taxon is given a name and a rank, although neither is a requirement...
to species status with the name Boletus plumbeoviolaceus. Noted Agaricales
Agaricales
The fungal order Agaricales, also known as gilled mushrooms , or euagarics, contains some of the most familiar types of mushrooms. The order has 33 extant families, 413 genera, and over 13000 described species, along with five extinct genera known only from the fossil record...
taxonomist Rolf Singer
Rolf Singer
Rolf Singer was a German-born mycologist and one of the most important taxonomists of gilled mushrooms in the 20th century....
later transferred the taxon
Taxon
|thumb|270px|[[African elephants]] form a widely-accepted taxon, the [[genus]] LoxodontaA taxon is a group of organisms, which a taxonomist adjudges to be a unit. Usually a taxon is given a name and a rank, although neither is a requirement...
to Tylopilus
Tylopilus
Tylopilus is a large genus of around 75 species of mycorrhizal bolete fungi separated from Boletus. Its best known member is the bitter bolete , the only species found in Europe. More species are found in North America, such as the edible species Tylopilus chromapes and T. alboater, and the...
in 1947, a genus characterized by a 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...
that is pink, or purplish (vinaceous), rather than brown as in Boletus.
The specific name "plumbeoviolaceus" is coined 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...
adjectives plumbeus ("leaden" or "lead-colored") and violaceus ("purple"). 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 "violet-grey bolete".
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
Basidiocarp
In fungi, a basidiocarp, basidiome or basidioma , is the sporocarp of a basidiomycete, the multicellular structure on which the spore-producing hymenium is borne. Basidiocarps are characteristic of the hymenomycetes; rusts and smuts do not produce such structures...
is 7 to 15 cm (2.8 to 5.9 in) in diameter, initially convex in shape but becoming centrally depressed, with a broadly arched and rounded margin. Young specimens are rather hard and firm, and the cap has a finely velvet-textured surface that soon wears off to become smooth. The color of the fruit body is violet when young, but dulls as it ages, becoming a dull violet-purplish-gray, then eventually chocolate-brown at maturity. 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 solid, white, and does not change color when cut or bruised. The taste is bitter, and the odor is not distinctive. Mycologist David Arora
David Arora
David Arora is an American mycologist, naturalist, and writer. He is the author of two popular books on mushroom identification, Mushrooms Demystified and All That the Rain Promises and More.......
calls the mushroom "beautiful, but bitter-tasting".
The tubes on the underside of the cap are 0.4 to 1.8 cm (0.15748031496063 to 0.708661417322835 in) deep, 2 or three per millimeter, depressed at the stem (resulting in an adnate attachment). The color of the pore surface is initially white, and it remains so for a while before turning a rosy color at maturity. 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 8 to 13 cm (3.1 to 5.1 in) long and 2.5 to 4 cm (0.984251968503937 to 1.6 in) thick, enlarged at the base, and sometimes bulbous. The surface is slightly reticulate at the top, and smooth lower of the stem. Its color is buff to light brown, often with darker brown bruises or stains, and it has whitish mycelium
Mycelium
thumb|right|Fungal myceliaMycelium is the vegetative part of a fungus, consisting of a mass of branching, thread-like hyphae. The mass of hyphae is sometimes called shiro, especially within the fairy ring fungi. Fungal colonies composed of mycelia are found in soil and on or within many other...
at the base. The flesh of the stem is white, and it does not change color when cut or bruised.
Microscopic characteristics
Collected in deposit, like 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 of T. plumbeoviolaceus appear to be a light pink to flesh color. When viewed with a light microscope, they are elliptical, with smooth walls and dimensions of 9.1–12.3 by 3.4–4.5 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 (cellular structures that produce the spores) are club-shaped, and measure about 26 by 6.5 µm. The cuticle of the cap (the pileipellis
Pileipellis
thumb|300px||right|The cuticle of some mushrooms, such as [[Russula mustelina]] shown here, can be peeled from the cap, and may be useful as an identification feature....
) is made of a tangle of smooth-walled, narrow, brownish hyphae. When stained in potassium hydroxide
Potassium hydroxide
Potassium hydroxide is an inorganic compound with the formula KOH, commonly called caustic potash.Along with sodium hydroxide , this colorless solid is a prototypical strong base. It has many industrial and niche applications. Most applications exploit its reactivity toward acids and its corrosive...
, the hyphal contents tend to form beads, while staining in Melzer's reagent
Melzer's Reagent
Melzer's reagent is a chemical reagent used by mycologists to assist with the identification of fungi.-Composition:...
causes the pigment to form globules. Cystidia are common in the hymenial
Hymenium
The hymenium is the tissue layer on the hymenophore of a fungal fruiting body where the cells develop into basidia or asci, which produce spores. In some species all of the cells of the hymenium develop into basidia or asci, while in others some cells develop into sterile cells called cystidia or...
tissue; they are swollen at the base and narrow at the apex (lageniform), measuring 30–40 µm long by 7–9 µm thick. Clamp connection
Clamp connection
A clamp connection is a structure formed by growing hyphal cells of certain fungi. It is created to ensure each septum, or segment of hypha separated by crossed walls, receives a set of differing nuclei, which are obtained through mating of hyphae of differing sexual types...
s are absent in the hypha
Hypha
A hypha is a long, branching filamentous structure of a fungus, and also of unrelated Actinobacteria. In most fungi, hyphae are the main mode of vegetative growth, and are collectively called a mycelium; yeasts are unicellular fungi that do not grow as hyphae.-Structure:A hypha consists of one or...
e.
Edibility
Like most Tyopilus species, the fruit bodies of T. plumbeoviolaceous are not recommended for consumption because of its bitter taste. The presence of a bitter bolete may spoil a meal, as the bitter taste does not disappear with cooking.Similar species
There are few other species that might be confused with Tylopilus plumbeoviolaceus; according to one source, it "is one of the most remarkable and easily identified boletes in the USA." Tylopilus violatinctus, found under both hardwoods and conifers and known from New York to MississippiMississippi
Mississippi is a U.S. state located in the Southern United States. Jackson is the state capital and largest city. The name of the state derives from the Mississippi River, which flows along its western boundary, whose name comes from the Ojibwe word misi-ziibi...
, has an appearance similar to T. plumbeoviolaceus. It can be distinguished by a paler, lilac-colored cap that, in older specimens, is discolored rusty purple along the edge of the cap. Its spores are 7–10 by 3–4 µm. Tylopilus violatinctus was not described until 1998, so some older literature may confuse the two similar species.
Young specimens of Tylopilus rubrobrunneus have a purplish cap, but unlike T. plumbeoviolaceous, their stems are never purple. The species Tylopilus microsporus, known only from China, is characterized by pale violet to violet cap, paler purple to purplish brown stem, and flesh color to pale purplish red pores. In addition to its different distribution, it can be distinguished from T. plumbeoviolaceus by its smaller spores. Another similar Asian species, T. obscureviolaceus, is only known from the Yaeyama Islands
Yaeyama Islands
The Yaeyama Islands are a group of islands in Okinawa Prefecture, Japan.The isles are the remotest part of Japan from the main islands and contains Japan's most southern and most western inhabited islands.The islands form the southern part of the volcanic Nansei Islands...
in southwestern Japan. It differs from T. plumbeoviolaceous in having a cap that does not fade in color to grayish or brownish when mature, shorter spores (6–7.2 by 3.3–4 µm), and other microscopic characteristics.
Habitat, distribution, and ecology
Tylopilus plumbeoviolaceous is a mycorrhizaMycorrhiza
A mycorrhiza is a symbiotic association between a fungus and the roots of a vascular plant....
l species, and the bulk of the fungus lives underground, associating in a mutualistic relationship with the roots of various tree species. The fruit bodies are found growing singly, scattered or clustered together during mid-summer to autumn in deciduous forests, often under beech
Beech
Beech is a genus of ten species of deciduous trees in the family Fagaceae, native to temperate Europe, Asia and North America.-Habit:...
or oak
Oak
An oak is a tree or shrub in the genus Quercus , of which about 600 species exist. "Oak" may also appear in the names of species in related genera, notably Lithocarpus...
trees; however, it sometimes occurs in mixed hardwood-conifer forests under hemlock
Tsuga
Tsuga is a genus of conifers in the family Pinaceae. The common name hemlock is derived from a perceived similarity in the smell of its crushed foliage to that of the unrelated plant poison hemlock....
. A preference for sandy soil has been noted in one source. In North America, the mushroom can be found east of the Rocky Mountains
Rocky Mountains
The Rocky Mountains are a major mountain range in western North America. The Rocky Mountains stretch more than from the northernmost part of British Columbia, in western Canada, to New Mexico, in the southwestern United States...
, ranging from Canada to Mexico. The species has also been collected in North Korea
North Korea
The Democratic People’s Republic of Korea , , is a country in East Asia, occupying the northern half of the Korean Peninsula. Its capital and largest city is Pyongyang. The Korean Demilitarized Zone serves as the buffer zone between North Korea and South Korea...
. Fruit bodies can serve as a food source for fungus-feeding 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...
flies.
Bioactive compounds
Two derivativesDerivative (chemistry)
In chemistry, a derivative is a compound that is derived from a similar compound by some chemical or physical process. In the past it was also used to mean a compound that can be imagined to arise from another compound, if one atom is replaced with another atom or group of atoms, but modern...
of ergosterol
Ergosterol
Ergosterol is a sterol found in fungi, and named for ergot, a common name for the members of the fungal genus Claviceps from which ergosterol was first isolated. Ergosterol does not occur in plant or animal cells...
have been isolated from the fruit bodies of T. plumbeoviolaceus: tylopiol A (3β-hydroxy-8α,9α-oxido-8,9-secoergosta-7,9(11),22-triene) and tylopiol B (3β-hydroxy-8α,9α-oxido-8,9-secoergosta-7,22dien-12-one). These sterols are unique to this species. Additionally, the compounds ergosta-7,22-dien-3β-ol, uridine
Uridine
Uridine is a molecule that is formed when uracil is attached to a ribose ring via a β-N1-glycosidic bond.If uracil is attached to a deoxyribose ring, it is known as a deoxyuridine....
, allitol, ergosterol, ergosterol 5α,8α-peroside, ergothioneine
Ergothioneine
Ergothioneine is a naturally occurring amino acid and is a thiourea derivative of histidine, containing a sulfur atom in the imidazole ring. This compound is made in rather few organisms, notably Actinobacteria and filamentous fungi. Ergothioneine was discovered in 1909 and named after the ergot...
, adenosine, and uracil
Uracil
Uracil is one of the four nucleobases in the nucleic acid of RNA that are represented by the letters A, G, C and U. The others are adenine, cytosine, and guanine. In RNA, uracil binds to adenine via two hydrogen bonds. In DNA, the uracil nucleobase is replaced by thymine.Uracil is a common and...
have been identified from the mushrooms.