Boletus amygdalinus
Encyclopedia
Boletus amygdalinus is a fungus
of the bolete family
found in western North America. The fruit bodies
, or mushroom
s, are characterized by their thick, red to brown cap
s, red pores, and the strong bluing reaction observed when the mushroom tissue is injured or cut. The cap can reach diameters of up to 10 cm (3.9 in) and the stem
9 cm (3.5 in) long by 3 cm (1.2 in) thick at maturity. This mushroom has been found in manzanita
and madrone woodlands of central California
north to southern Oregon
. Although the edibility
of the mushroom is not known with certainty, it may be poisonous, and is not recommended for consumption. Other similar red-pored, bluing boletes from North America, including B. eastwoodiae, B. luridiformis, and B. subvelutipes, can be distinguished from B. amygdalinus either by the color of the cap, the degree of reticulation on the stem (a network of raised ridges), or by location.
in 1965, based on specimens he found in Napa County, California, on 23 November, 1963. In 1975, Thiers changed the name to Boletus amygdalinus (a nomen nudum
) as he discovered that the epithet had already been used for a different bolete found in Yunnan, China, published in 1948.
In Latin
, amygdaline means relating to or resembling an almond
.
that can reach diameters of 6 to 10 cm (2.4 to 3.9 in) at maturity. The surface of the cap is dry, and matted with fibers; the cap color of young specimens is red, but the mushrooms typically change to more brownish tones as they mature. The margin of the cap starts out curved inwards (incurved) and gradually becomes curved downwards (decurved) with age. The pores on the underside of the cap are 0.5 to 1 mm (0.0196850393700787 to 0.0393700787401575 in) wide, angular, and red or red-orange, while the tubes are 1 to 1.5 cm (0.393700787401575 to 0.590551181102362 in) deep.
The stem
lacks a netted pattern (reticulation) and is yellow in color but is often covered by red hairs, especially near the base. The stem is either equal in width throughout, or thicker in the middle; it reaches dimensions of 5 – long by 1 – thick. The base of the stem is typically bent. The flesh
is 1 to 2 cm (0.393700787401575 to 0.78740157480315 in) thick, and yellow in color, but like all parts of the mushroom, will stain blue immediately upon bruising or cutting. Both the odor and taste of the fruit bodies are mild.
Although the edibility
of B. amygdalinus is not known with certainty, authorities often recommend to avoid consuming blue-staining, red-pored boletes, as several are poisonous. The species was implicated in one group of poisonings in California in 1996–97, but because of the nature of the symptoms experienced, there was probably more than one type of mushroom consumed.
. The spores
are thick-walled, smooth, and ellipsoid to somewhat spindle-shaped, with dimensions of 11.2–16 by 5.2–8 µm
. They become dark ochraceous when stained with Melzer's reagent
, and, because of the occasional presence of two large vacuole
s, may appear as if they are two-celled. The basidia (the spore-bearing cells) are club-shaped, contain numerous vacuoles, and measure 30–35 by 9–11 µm. Cystidia are present on sides of the tubes, and they measure 45–54 by 10–12 µm. Clamp connection
s are not present in the hyphae of B. amygdalinus.
Various chemical color tests
can be used to help identify fruit bodies suspected to be B. amygdalinus. A drop of dilute potassium hydroxide
(KOH) will turn the cap flesh dingy orange, while it turns the cap cuticle red, or darker. Ammonia
(as ammonium hydroxide
, NH4OH) produces a dingy yellow on the flesh, and brown on the cap. Iron sulphate
(FeSO4) produces either no change to a pale grey color with both the flesh and the cuticle. Hydrochloric acid
(HCl) causes the flesh to turn orange or pink, but has no color reaction with the cuticle.
, manzanita
and madrone in California
, and Oregon
. Fruiting occurs after the onset of autumn
rains, usually between the October and January. The mushroom can be difficult to spot, as its cap is similar in coloring to the leaves of the madrone tree with which it is associated, and because the mushroom is frequently buried under leaves.
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...
found in western North America. 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...
, or mushroom
Mushroom
A mushroom is the fleshy, spore-bearing fruiting body of a fungus, typically produced above ground on soil or on its food source. The standard for the name "mushroom" is the cultivated white button mushroom, Agaricus bisporus; hence the word "mushroom" is most often applied to those fungi that...
s, are characterized by their thick, red to 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...
s, red pores, and the strong bluing reaction observed when the mushroom tissue is injured or cut. The cap can reach diameters of up to 10 cm (3.9 in) 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...
9 cm (3.5 in) long by 3 cm (1.2 in) thick at maturity. This mushroom has been found in manzanita
Manzanita
Manzanita is a common name for many species of the genus Arctostaphylos. They are evergreen shrubs or small trees present in the chaparral biome of western North America, where they occur from southern British Columbia, Washington to California, Arizona and New Mexico in the United States, and...
and madrone woodlands of central California
California
California is a state located on the West Coast of the United States. It is by far the most populous U.S. state, and the third-largest by land area...
north to southern Oregon
Oregon
Oregon is a state in the Pacific Northwest region of the United States. It is located on the Pacific coast, with Washington to the north, California to the south, Nevada on the southeast and Idaho to the east. The Columbia and Snake rivers delineate much of Oregon's northern and eastern...
. Although the edibility
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...
of the mushroom is not known with certainty, it may be poisonous, and is not recommended for consumption. Other similar red-pored, bluing boletes from North America, including B. eastwoodiae, B. luridiformis, and B. subvelutipes, can be distinguished from B. amygdalinus either by the color of the cap, the degree of reticulation on the stem (a network of raised ridges), or by location.
Taxonomy
The species was first named Boletus puniceus by Harry D. ThiersHarry D. Thiers
Harry Delbert Thiers, born January 22, 1919 in Fort McKavett, Texas, died August 8, 2000 in Ohio, was an American mycologist who studied and named a great many fungi of native to North America, particularly California. Thiers taught mycology at San Francisco State University for many years, and a...
in 1965, based on specimens he found in Napa County, California, on 23 November, 1963. In 1975, Thiers changed the name to Boletus amygdalinus (a nomen nudum
Nomen nudum
The phrase nomen nudum is a Latin term, meaning "naked name", used in taxonomy...
) as he discovered that the epithet had already been used for a different bolete found in Yunnan, China, published in 1948.
In 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...
, amygdaline means relating to or resembling an almond
Almond
The almond , is a species of tree native to the Middle East and South Asia. Almond is also the name of the edible and widely cultivated seed of this tree...
.
Description
Boletus amygdalinus is a large solid mushroom with a convex to somewhat flattened, irregular 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...
that can reach diameters of 6 to 10 cm (2.4 to 3.9 in) at maturity. The surface of the cap is dry, and matted with fibers; the cap color of young specimens is red, but the mushrooms typically change to more brownish tones as they mature. The margin of the cap starts out curved inwards (incurved) and gradually becomes curved downwards (decurved) with age. The pores on the underside of the cap are 0.5 to 1 mm (0.0196850393700787 to 0.0393700787401575 in) wide, angular, and red or red-orange, while the tubes are 1 to 1.5 cm (0.393700787401575 to 0.590551181102362 in) deep.
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...
lacks a netted pattern (reticulation) and is yellow in color but is often covered by red hairs, especially near the base. The stem is either equal in width throughout, or thicker in the middle; it reaches dimensions of 5 – long by 1 – thick. The base of the stem is typically bent. 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 1 to 2 cm (0.393700787401575 to 0.78740157480315 in) thick, and yellow in color, but like all parts of the mushroom, will stain blue immediately upon bruising or cutting. Both the odor and taste of the fruit bodies are mild.
Although the edibility
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...
of B. amygdalinus is not known with certainty, authorities often recommend to avoid consuming blue-staining, red-pored boletes, as several are poisonous. The species was implicated in one group of poisonings in California in 1996–97, but because of the nature of the symptoms experienced, there was probably more than one type of mushroom consumed.
Microscopic characteristics
B. amygdalinus produces a dark olive-brown spore printSpore print
thumb|300px|right|Making a spore print of the mushroom Volvariella volvacea shown in composite: mushroom cap laid on white and dark paper; cap removed after 24 hours showing pinkish-tan spore print...
. The spores
Basidiospore
A basidiospore is a reproductive spore produced by Basidiomycete fungi. Basidiospores typically each contain one haploid nucleus that is the product of meiosis, and they are produced by specialized fungal cells called basidia. In grills under a cap of one common species in the phylum of...
are thick-walled, smooth, and ellipsoid to somewhat spindle-shaped, with dimensions of 11.2–16 by 5.2–8 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...
. They become dark ochraceous 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, because of the occasional presence of two large vacuole
Vacuole
A vacuole is a membrane-bound organelle which is present in all plant and fungal cells and some protist, animal and bacterial cells. Vacuoles are essentially enclosed compartments which are filled with water containing inorganic and organic molecules including enzymes in solution, though in certain...
s, may appear as if they are two-celled. The basidia (the spore-bearing cells) are club-shaped, contain numerous vacuoles, and measure 30–35 by 9–11 µm. Cystidia are present on sides of the tubes, and they measure 45–54 by 10–12 µm. 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 not present in the hyphae of B. amygdalinus.
Various chemical color tests
Chemical 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...
can be used to help identify fruit bodies suspected to be B. amygdalinus. A drop of dilute 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...
(KOH) will turn the cap flesh dingy orange, while it turns the cap cuticle red, or darker. Ammonia
Ammonia
Ammonia is a compound of nitrogen and hydrogen with the formula . It is a colourless gas with a characteristic pungent odour. Ammonia contributes significantly to the nutritional needs of terrestrial organisms by serving as a precursor to food and fertilizers. Ammonia, either directly or...
(as 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...
, NH4OH) produces a dingy yellow on the flesh, and brown on the cap. Iron sulphate
Iron(II) sulfate
Iron sulfate or ferrous sulfate is the chemical compound with the formula FeSO4. Known since ancient times as copperas and as green vitriol, the blue-green heptahydrate is the most common form of this material...
(FeSO4) produces either no change to a pale grey color with both the flesh and the cuticle. Hydrochloric acid
Hydrochloric acid
Hydrochloric acid is a solution of hydrogen chloride in water, that is a highly corrosive, strong mineral acid with many industrial uses. It is found naturally in gastric acid....
(HCl) causes the flesh to turn orange or pink, but has no color reaction with the cuticle.
Similar species
There are several other red-pored, bluing boletes that could be confused with B. amygdalinus. The poisonous European species B. satanas and its North American counterpart B. eastwoodiae have lighter colored caps and a reticulate pattern on the stem. B. subvelutipes is a highly variable species from eastern North America that includes red in its range of cap colors, and has a fuzzy coating of hairs near the base of its stem; it may represent a group of species. Another similar species is B. luridiformis, found in North America and Northern Europe under both broadleaf trees and conifers. Unlike B. amygdalinus, however, B. luridiformis has a dark brown to nearly blackish-brown cap, and a yellow stem with a dense covering of red pruina (dots).Distribution and habitat
Boletus amygdalinus mushrooms grow on the ground in groups, or scattered about. The fungus has been reported from low-elevation hardwood forests composed of live oakLive oak
Live oak , also known as the southern live oak, is a normally evergreen oak tree native to the southeastern United States...
, manzanita
Manzanita
Manzanita is a common name for many species of the genus Arctostaphylos. They are evergreen shrubs or small trees present in the chaparral biome of western North America, where they occur from southern British Columbia, Washington to California, Arizona and New Mexico in the United States, and...
and madrone in California
California
California is a state located on the West Coast of the United States. It is by far the most populous U.S. state, and the third-largest by land area...
, and Oregon
Oregon
Oregon is a state in the Pacific Northwest region of the United States. It is located on the Pacific coast, with Washington to the north, California to the south, Nevada on the southeast and Idaho to the east. The Columbia and Snake rivers delineate much of Oregon's northern and eastern...
. Fruiting occurs after the onset of autumn
Autumn
Autumn is one of the four temperate seasons. Autumn marks the transition from summer into winter usually in September or March when the arrival of night becomes noticeably earlier....
rains, usually between the October and January. The mushroom can be difficult to spot, as its cap is similar in coloring to the leaves of the madrone tree with which it is associated, and because the mushroom is frequently buried under leaves.