Boletus mirabilis
Encyclopedia
Boletus mirabilis, commonly
known as the admirable bolete, the bragger's bolete, and the velvet top, is an edible
species of fungus
in the Boletaceae
mushroom family
. The fruit body
has several characteristics with which it may be identified: a dark reddish-brown cap
; yellow to greenish-yellow pores on the undersurface of the cap; and a reddish-brown stem
with long narrow reticulations. Boletus mirabilis is found in coniferous forests along the Pacific Coast
of North America
, and in Asia
. Unusual for boletes, B. mirabilis sometimes appears to fruit on the wood or woody debris of Hemlock
, suggesting a saprobic lifestyle. Despite occasional appearances to the contrary, Boletus mirabilis is mycorrhiza
l, and forms close mutualistic associations with hemlock roots. There has been some disagreement in the literature as to whether the mushroom should be placed in the closely related genera Boletus
or Boletellus
.
Boletus mirabilis was first described by American mycologist William Alphonso Murrill in 1912 as Ceriomyces mirabilis, based on specimens found in Seattle, Washington. In a subsequent publication that same year, he switched the genus
to Boletus
. In 1940, fungal taxonomist Rolf Singer
transferred the taxon
to the genus Xerocomus
; five years later he switched it to Boletellus
. However, many modern mycologists do not recognize the distinction between Boletus and Boletellus. In 1966, American mycologist Harry Delbert Thiers wrote about the issue in his survey of California boletes:
Nine years later, after further consideration, Thiers changed his mind:
, newly described in 2004 by Swiss mycologist Egon Horak, so Heimioporus mirabilis is considered another synonym
.
The specific epithet mirabilis means "admirable" or "marvelous". Boletus mirabilis is commonly
known as the "admirable bolete", the "bragger's bolete", and the "velvet top".
Based on analysis of ribosomal DNA
sequences for a number of taxa
in the Boletales
order, B. mirabilis is most closely related to species such as Boletus edulis
, Phylloporus rhodoxanthus
, and Tylopilus felleus
. Within the Boletales clade
(a group of related species roughly equivalent to the Boletales order), these species are all in the so-called "boletoid radiation", a group of taxa that are thought to have diverged evolutionarily from a single boletoid ancestor.
, which form the active feeding and growing structures of the fungus. The mushrooms, or fruit bodies
are created solely for the production of spore
s by which the fungus reproduces itself. The caps
of the fruit bodies are up to 15 cm (5.9 in) in diameter, red or brownish-red in color, initially convex but flattening out as they develop. The cap is fleshy, with a rough surface that is slippery or slimy in young specimens, or in moist environments. Older specimens generally have dry and velvety cap surfaces. The texture of the cap surface is rough, at first because of flattened-down (appressed) fibrils, and later with bent-back (recurved) scales or sometimes with cracked rough patches that resemble dried cracked mud. Young specimens may have a small flap of thin tissue attached to the margin or edge of the cap, remnants of a reduced partial veil
. The surface is covered with tufts of soft woolly hairs, and has persistent papilla
e.
The tubes underneath the cap are up to 2.5 cm (0.984251968503937 in) long, and are initially pale yellowish before becoming greenish-yellow with age, or mustard-yellow if injured. The pores have diameters of 1–2 mm
. The flesh
can be pale pink, yellow, or white in color, firm but watery, thick, and either not changing color or becoming deeper yellow with bruising. The flesh is 1 to 1.5 cm (0.393700787401575 to 0.590551181102362 in) thick at the junction of the stem with the cap.
The stem
is up to 12 cm (4.7 in) long, usually thickest at the base and tapering upward, up to 4 cm (1.6 in) thick below and 0.5 to 1 cm (0.196850393700787 to 0.393700787401575 in) at the apex. It typically starts out with a bulbous shape but becomes more equal in width throughout as it matures. The surface is dry, often roughened and pitted, and with a network of grooves or ridges (striations) or reticulations near the top of the stem. It is about the same color as the cap, but will bruise to a darker reddish-brown near the base. The stem is solid (that is, not hollow), and its flesh pale purplish at the top, but yellowish below. Mycelium at the base of the stem is also yellow.
, the spores
of B. mirabilis are olive-brown. Viewed with a microscope, the spores
are spindle-shaped to roughly elliptical, with smooth, thick walls, and have dimensions of 18–22 by 7–9 µm
. Overholts' 1940 publication on the species reported spore dimensions of 20–26 by 8–9 µm. The basidia (spore-bearing cells) are club-shaped, hyaline
(translucent), 4-spored, and have dimensions of 31–36 by 7–11 µm. Cystidia
(sterile cells on the face of a gill) are thin-walled, and measure 60–90 by 10–18 µm. There are no clamp connection
s present in the hyphae.
, yet tasteless according to Murrill, who also noted "this is one of the most difficult species to preserve, owing to its extremely juicy consistency". In contrast, modern field guide
s suggest this species to be an excellent edible. The Polish Heritage Cookery book opines that in taste, only Boletus edulis
surpasses it. When sauteed
in butter, the flesh has been noted to have a lemony taste. However, field specimens covered with a white mold, Sepedonium ampullosporum, should not be consumed.
are sometimes used to rapidly distinguish between closely related or morphologically
similar species of mushrooms, or, in some cases, as characters to group species into subsections of a genus. Pigment
s present in the fungal hyphae are dissolved or react differently with various chemicals, and the color reactions may be used as taxonomic characters. When a drop of 10% aqueous solution of ammonium hydroxide
is applied to the cap of B. mirabilis, the tissue turns a fleeting pink color that fades away. If a drop of commercial bleach
(calcium hypochlorite) is applied, the tissue loses its color and becomes a pale blue.
and Strobilomyces strobilaceous, but the scales are more rigid with a somewhat conical shape. It can be distinguished from these two species by both its bay-brown color, and the absence of a veil
. Both of the other species mentioned possess a conspicuous veil
, and the former is tan to brown with a pinkish tint, while the latter is dark brown or black. Boletus edulis is separated from B. mirabilis by the color and texture of the cap, tubes and stem. Boletus coniferarum turns blue when bruised and has a very bitter taste. Boletus projectellus is also similar in appearance to Boletus mirabilis, but is found in eastern North America.
and western red cedar. The fungus is strongly suspected to form mycorrhiza
l associations with hemlock, although standard attempts at growing B. mirabilis mycorrhizae in laboratory culture
have failed. Although fruit bodies are sometimes found growing on logs with advanced brown cubical rot—a trait suggestive of cellulose
-decomposing saprobic
fungi—the rotten wood harboring the fungi typically contains abundant conifer roots. It has been suggested that B. mirabilis has specifically adapted to this niche to reduce competition for nutrients with other mycorrhizal fungi, and further, that the inability to culture mycorrhizae in the lab using standard techniques may be because certain physical or chemical characteristics of the wood with brown cubical rot are required for fungal growth.
Boletus mirabilis, which usually appears from late summer to autumn, is distributed in the hemlock forests of the Pacific Coast Ranges
from Northern California
to Alaska
, the Cascade Range
, as well as in interior forests such as in Manitoba
. It has a disjunct distribution
, as it has been also been collected in Japan
and Taiwan
.
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 admirable bolete, the bragger's bolete, and the velvet top, is an 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...
species of 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...
in the Boletaceae
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...
mushroom family
Family (biology)
In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...
. 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...
has several characteristics with which it may be identified: a dark reddish-brown 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...
; yellow to greenish-yellow pores on the undersurface of the cap; and a reddish-brown 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...
with long narrow reticulations. Boletus mirabilis is found in coniferous forests along the Pacific Coast
Pacific Coast
A country's Pacific coast is the part of its coast bordering the Pacific Ocean.-The Americas:Countries on the western side of the Americas have a Pacific coast as their western border.* Geography of Canada* Geography of Chile* Geography of Colombia...
of North America
North America
North America is a continent wholly within the Northern Hemisphere and almost wholly within the Western Hemisphere. It is also considered a northern subcontinent of the Americas...
, and in Asia
Asia
Asia is the world's largest and most populous continent, located primarily in the eastern and northern hemispheres. It covers 8.7% of the Earth's total surface area and with approximately 3.879 billion people, it hosts 60% of the world's current human population...
. Unusual for boletes, B. mirabilis sometimes appears to fruit on the wood or woody debris of 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....
, suggesting a saprobic lifestyle. Despite occasional appearances to the contrary, Boletus mirabilis is mycorrhiza
Mycorrhiza
A mycorrhiza is a symbiotic association between a fungus and the roots of a vascular plant....
l, and forms close mutualistic associations with hemlock roots. There has been some disagreement in the literature as to whether the mushroom should be placed in the closely related genera Boletus
Boletus
Boletus is a genus of mushroom, comprising over 100 species. The genus Boletus was originally broadly defined and described by Elias Magnus Fries in 1821, essentially containing all fungi with pores...
or Boletellus
Boletellus
Boletellus is a genus of fungi in the family Boletaceae. The genus has a widespread distribution, especially in subtropical regions, and contains about 50 species. The genus was first described by American mycologist William Alphonso Murrill in 1909...
.
Taxonomy and phylogeny
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...
to Boletus
Boletus
Boletus is a genus of mushroom, comprising over 100 species. The genus Boletus was originally broadly defined and described by Elias Magnus Fries in 1821, essentially containing all fungi with pores...
. In 1940, fungal 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....
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 the genus Xerocomus
Xerocomus
Xerocomus is a genus of fungi which is closely related to Boletus. Many mycologists do not recognize the distinction.Most members of Xerocomus are edible.Ladurner and Simonini published a monograph on Xerocomus in 2003....
; five years later he switched it to Boletellus
Boletellus
Boletellus is a genus of fungi in the family Boletaceae. The genus has a widespread distribution, especially in subtropical regions, and contains about 50 species. The genus was first described by American mycologist William Alphonso Murrill in 1909...
. However, many modern mycologists do not recognize the distinction between Boletus and Boletellus. In 1966, American mycologist Harry Delbert Thiers wrote about the issue in his survey of California boletes:
"The proper disposition of this species in the present taxonomic scheme of the boletes is somewhat debatable. ... The distinction between Boletus and Boletellus is not so clear-cut. The spores are typically smooth which, in conjunction with the divergent tube trama, dry to moist pileus and yellow tubes, seem to place it very convincingly in Boletus. However, the present disposition in Boletellus seems most satisfactory to me. The sporocarps have the stature and general appearance of other members of that genus such as Boletellus russellii and B. ananas (Curt.) Murr. These similarities include the disproportionately long stipe which is frequently shaggy-reticulate and constricted at the apex, and a comparatively small pileus."
Nine years later, after further consideration, Thiers changed his mind:
"In an earlier paper this species was considered to belong to the genus Boletellus because of its stature, general appearance, and because some workers had reported the spores as being obscurely punctate or roughened. Repeated examinations of California material have failed to reveal any roughened spores and since, in modern concepts Boletellus is restricted to species having such spores, it has been placed back in Boletus."The species has also been placed in genus Heimioporus
Heimioporus
Heimioporus is a genus of fungi in the Boletaceae family. The genus is widely distributed in tropical and subtropical regions, and contains about 15 species.-Species:*Heimioporus alveolatus*Heimioporus anguiformis*Heimioporus betula...
, newly described in 2004 by Swiss mycologist Egon Horak, so Heimioporus mirabilis is considered another synonym
Synonym (taxonomy)
In scientific nomenclature, a synonym is a scientific name that is or was used for a taxon of organisms that also goes by a different scientific name. For example, Linnaeus was the first to give a scientific name to the Norway spruce, which he called Pinus abies...
.
The specific epithet mirabilis means "admirable" or "marvelous". Boletus mirabilis 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 "admirable bolete", the "bragger's bolete", and the "velvet top".
Based on analysis of ribosomal DNA
Ribosomal DNA
Ribosomal DNA codes for ribosomal RNA. The ribosome is an intracellular macromolecule that produces proteins or polypeptide chains. The ribosome itself consists of a composite of proteins and RNA. As shown in the figure, rDNA consists of a tandem repeat of a unit segment, an operon, composed of...
sequences for a number of taxa
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...
in the Boletales
Boletales
The Boletales are an order of Agaricomycetes, containing over 1300 species with a diverse array of fruiting body types. The boletes are the best known members of this group, and until recently, the Boletales were thought to only contain boletes...
order, B. mirabilis is most closely related to species such as Boletus edulis
Boletus edulis
Boletus edulis, commonly known as penny bun, porcino or cep, is a basidiomycete fungus, and the type species of the genus Boletus. Widely distributed in the Northern Hemisphere across Europe, Asia, and North America, it does not occur naturally in the Southern Hemisphere, although it has been...
, Phylloporus rhodoxanthus
Phylloporus rhodoxanthus
Phylloporus rhodoxanthus, commonly known as the gilled bolete, is a species of fungus in the Boletaceae family. As suggested by its common name, the distinctive feature of this species is its yellow gills—an unusual feature on a bolete mushroom....
, and Tylopilus felleus
Tylopilus felleus
Tylopilus felleus, formerly Boletus felleus, is a fungus of the bolete family, found in Northern Europe and North America. Although it is not poisonous, it is not considered edible, due to its overwhelming bitterness.-Taxonomy:...
. Within the Boletales clade
Clade
A clade is a group consisting of a species and all its descendants. In the terms of biological systematics, a clade is a single "branch" on the "tree of life". The idea that such a "natural group" of organisms should be grouped together and given a taxonomic name is central to biological...
(a group of related species roughly equivalent to the Boletales order), these species are all in the so-called "boletoid radiation", a group of taxa that are thought to have diverged evolutionarily from a single boletoid ancestor.
Description
The bulk of Boletellus mirabilis is typically hidden from sight, existing as masses of almost invisible fungal threads called myceliumMycelium
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...
, which form the active feeding and growing structures of the fungus. The mushrooms, or 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...
are created solely for the production of 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 by which the fungus reproduces itself. The caps
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...
of the fruit bodies are up to 15 cm (5.9 in) in diameter, red or brownish-red in color, initially convex but flattening out as they develop. The cap is fleshy, with a rough surface that is slippery or slimy in young specimens, or in moist environments. Older specimens generally have dry and velvety cap surfaces. The texture of the cap surface is rough, at first because of flattened-down (appressed) fibrils, and later with bent-back (recurved) scales or sometimes with cracked rough patches that resemble dried cracked mud. Young specimens may have a small flap of thin tissue attached to the margin or edge of the cap, remnants of a reduced 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...
. The surface is covered with tufts of soft woolly hairs, and has persistent papilla
Plant cuticle
Plant cuticles are a protective waxy covering produced only by the epidermal cells of leaves, young shoots and all other aerial plant organs without periderm...
e.
The tubes underneath the cap are up to 2.5 cm (0.984251968503937 in) long, and are initially pale yellowish before becoming greenish-yellow with age, or mustard-yellow if injured. The pores have diameters of 1–2 mm
Millimetre
The millimetre is a unit of length in the metric system, equal to one thousandth of a metre, which is the SI base unit of length....
. 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....
can be pale pink, yellow, or white in color, firm but watery, thick, and either not changing color or becoming deeper yellow with bruising. The flesh is 1 to 1.5 cm (0.393700787401575 to 0.590551181102362 in) thick at the junction of the stem with the cap.
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 up to 12 cm (4.7 in) long, usually thickest at the base and tapering upward, up to 4 cm (1.6 in) thick below and 0.5 to 1 cm (0.196850393700787 to 0.393700787401575 in) at the apex. It typically starts out with a bulbous shape but becomes more equal in width throughout as it matures. The surface is dry, often roughened and pitted, and with a network of grooves or ridges (striations) or reticulations near the top of the stem. It is about the same color as the cap, but will bruise to a darker reddish-brown near the base. The stem is solid (that is, not hollow), and its flesh pale purplish at the top, but yellowish below. Mycelium at the base of the stem is also yellow.
Microscopic characteristics
Collected in depositSpore 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 B. mirabilis are olive-brown. Viewed with a microscope, 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...
are spindle-shaped to roughly elliptical, with smooth, thick walls, and have dimensions of 18–22 by 7–9 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...
. Overholts' 1940 publication on the species reported spore dimensions of 20–26 by 8–9 µm. The basidia (spore-bearing cells) are club-shaped, 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), 4-spored, and have dimensions of 31–36 by 7–11 µm. Cystidia
Cystidium
A cystidium is a relatively large cell found on the hymenium of a basidiomycete , often between clusters of basidia. Since cystidia have highly varied and distinct shapes that are often unique to a particular species or genus, they are a useful micromorphological characteristic in the...
(sterile cells on the face of a gill) are thin-walled, and measure 60–90 by 10–18 µm. There are no 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 present in the hyphae.
Edibility
Boletus mirabilis is 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...
, yet tasteless according to Murrill, who also noted "this is one of the most difficult species to preserve, owing to its extremely juicy consistency". In contrast, modern field guide
Field guide
A field guide is a book designed to help the reader identify wildlife or other objects of natural occurrence . It is generally designed to be brought into the 'field' or local area where such objects exist to help distinguish between similar objects...
s suggest this species to be an excellent edible. The Polish Heritage Cookery book opines that in taste, only Boletus edulis
Boletus edulis
Boletus edulis, commonly known as penny bun, porcino or cep, is a basidiomycete fungus, and the type species of the genus Boletus. Widely distributed in the Northern Hemisphere across Europe, Asia, and North America, it does not occur naturally in the Southern Hemisphere, although it has been...
surpasses it. When sauteed
Sautéing
Sautéing is a method of cooking food, that uses a small amount of fat in a shallow pan over relatively high heat. Ingredients are usually cut into pieces or thinly sliced to facilitate fast cooking. The primary mode of heat transfer during sautéing is conduction between the pan and the food being...
in butter, the flesh has been noted to have a lemony taste. However, field specimens covered with a white mold, Sepedonium ampullosporum, should not be consumed.
Chemical reactions
Chemical testsChemical tests in mushroom identification
Chemical tests in mushroom identification are methods that aid in determining the variety of some fungi. The most useful tests are Melzer's reagent and potassium hydroxide.- Ammonia :Household ammonia can be used. A couple of drops are placed on the flesh...
are sometimes used to rapidly distinguish between closely related or morphologically
Morphology (biology)
In biology, morphology is a branch of bioscience dealing with the study of the form and structure of organisms and their specific structural features....
similar species of mushrooms, or, in some cases, as characters to group species into subsections of a genus. Pigment
Pigment
A pigment is a material that changes the color of reflected or transmitted light as the result of wavelength-selective absorption. This physical process differs from fluorescence, phosphorescence, and other forms of luminescence, in which a material emits light.Many materials selectively absorb...
s present in the fungal hyphae are dissolved or react differently with various chemicals, and the color reactions may be used as taxonomic characters. When a drop of 10% aqueous solution of ammonium hydroxide
Ammonium hydroxide
Ammonia solution, also known as ammonium hydroxide, ammonia water, ammonical liquor, ammonia liquor, aqua ammonia, aqueous ammonia, or simply ammonia, is a solution of ammonia in water. It can be denoted by the symbols NH3...
is applied to the cap of B. mirabilis, the tissue turns a fleeting pink color that fades away. If a drop of commercial bleach
Bleach
Bleach refers to a number of chemicals that remove color, whiten, or disinfect, often via oxidation. Common chemical bleaches include household chlorine bleach , lye, oxygen bleach , and bleaching powder...
(calcium hypochlorite) is applied, the tissue loses its color and becomes a pale blue.
Similar species
Boletus mirabilis differs from other boletus mushrooms in the covering of the cap, which superficially resembles that found on the surface of Boletellus ananasBoletellus ananas
Boletellus ananas, commonly known as the pineapple bolete, is a mushroom in the Boletaceae family, and the type species of the genus Boletellus. It is distributed in southeastern North America, northeastern South America, Asia, and New Zealand, where it grows scattered or in groups on the ground,...
and Strobilomyces strobilaceous, but the scales are more rigid with a somewhat conical shape. It can be distinguished from these two species by both its bay-brown color, and the absence of a 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...
. Both of the other species mentioned possess a conspicuous 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...
, and the former is tan to brown with a pinkish tint, while the latter is dark brown or black. Boletus edulis is separated from B. mirabilis by the color and texture of the cap, tubes and stem. Boletus coniferarum turns blue when bruised and has a very bitter taste. Boletus projectellus is also similar in appearance to Boletus mirabilis, but is found in eastern North America.
Habitat and distribution
The fruit bodies of Boletus mirabilis grow solitarily, scattered, or sometimes in small groups on the ground or on well-decayed conifer logs, especially of western and mountain hemlock, but occasionally also Douglas-firDouglas-fir
Douglas-fir is one of the English common names for evergreen coniferous trees of the genus Pseudotsuga in the family Pinaceae. Other common names include Douglas tree, and Oregon pine. There are five species, two in western North America, one in Mexico, and two in eastern Asia...
and western red cedar. The fungus is strongly suspected to form mycorrhiza
Mycorrhiza
A mycorrhiza is a symbiotic association between a fungus and the roots of a vascular plant....
l associations with hemlock, although standard attempts at growing B. mirabilis mycorrhizae in laboratory culture
Microbiological culture
A microbiological culture, or microbial culture, is a method of multiplying microbial organisms by letting them reproduce in predetermined culture media under controlled laboratory conditions. Microbial cultures are used to determine the type of organism, its abundance in the sample being tested,...
have failed. Although fruit bodies are sometimes found growing on logs with advanced brown cubical rot—a trait suggestive of cellulose
Cellulose
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....
-decomposing saprobic
Detritivore
Detritivores, also known as detritophages or detritus feeders or detritus eaters or saprophages, are heterotrophs that obtain nutrients by consuming detritus . By doing so, they contribute to decomposition and the nutrient cycles...
fungi—the rotten wood harboring the fungi typically contains abundant conifer roots. It has been suggested that B. mirabilis has specifically adapted to this niche to reduce competition for nutrients with other mycorrhizal fungi, and further, that the inability to culture mycorrhizae in the lab using standard techniques may be because certain physical or chemical characteristics of the wood with brown cubical rot are required for fungal growth.
Boletus mirabilis, which usually appears from late summer to autumn, is distributed in the hemlock forests of the Pacific Coast Ranges
Pacific Coast Ranges
The Pacific Coast Ranges and the Pacific Mountain System are the series of mountain ranges that stretch along the West Coast of North America from Alaska south to Northern and Central Mexico...
from Northern California
Northern California
Northern California is the northern portion of the U.S. state of California. The San Francisco Bay Area , and Sacramento as well as its metropolitan area are the main population centers...
to Alaska
Alaska
Alaska is the largest state in the United States by area. It is situated in the northwest extremity of the North American continent, with Canada to the east, the Arctic Ocean to the north, and the Pacific Ocean to the west and south, with Russia further west across the Bering Strait...
, the Cascade Range
Cascade Range
The Cascade Range is a major mountain range of western North America, extending from southern British Columbia through Washington and Oregon to Northern California. It includes both non-volcanic mountains, such as the North Cascades, and the notable volcanoes known as the High Cascades...
, as well as in interior forests such as in Manitoba
Manitoba
Manitoba is a Canadian prairie province with an area of . The province has over 110,000 lakes and has a largely continental climate because of its flat topography. Agriculture, mostly concentrated in the fertile southern and western parts of the province, is vital to the province's economy; other...
. It 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...
, as it has been also been collected in Japan
Japan
Japan is an island nation in East Asia. Located in the Pacific Ocean, it lies to the east of the Sea of Japan, China, North Korea, South Korea and Russia, stretching from the Sea of Okhotsk in the north to the East China Sea and Taiwan in the south...
and Taiwan
Taiwan
Taiwan , also known, especially in the past, as Formosa , is the largest island of the same-named island group of East Asia in the western Pacific Ocean and located off the southeastern coast of mainland China. The island forms over 99% of the current territory of the Republic of China following...
.
External links
- mushroomhobby.com Several photos