Lactarius repraesentaneus
Encyclopedia
Lactarius repraesentaneus, commonly known as the northern bearded milkcap, the northern milkcap, or the purple-staining milkcap, is a species of fungus
in the Russulaceae
family. It has a northerly distribution, and is found in temperate
regions of North America and Europe, associated with spruce
trees. Distinguishing features of its fruit body
include the large orange-yellow cap
up to 18 cm (7.1 in) wide, cream to pale yellow gills, and a yellow coarsely-pitted stem
that is up to 12 cm (4.7 in) long and 3 cm (1.2 in) thick. Cut fruit bodies ooze a white latex
that will stain mushroom tissue lilac
to purple. Several chemicals have been isolated and identified from the fruit bodies that can modify the growth of plants, and the mushroom also has antibiotic
activity against Staphylococcus aureus
. L. repraesentaneus is poisonous, and consumption causes stomach aches.
in 1885, based on material collected from Bavaria
. The variety Lactarius scrobiculatus var. repraesentaneus, proposed by Killermann in 1933, is considered a synonym
. Rolf Singer
in 1942 defined the subspecies
L. repraesentaneus ssp. speciosus to include fruit bodies with matted fibers ("felt") arranged in concentric rings on the cap (zonate), in comparison with the nominate subspecies, where in young specimens the felt was evenly distributed on the cap surface, only becoming zonate at the cap margins in maturity.
According to the classification proposed by Lexemuel Ray Hesler
and Alexander H. Smith
in their 1979 monograph
of North American Lactarius species, L. repraesentaneus belongs in the stirps Speciosus of the section Aspideini, of the subgenus
Piperites of genus Lactarius
. Other species in stirps Speciosus include L. dispersus, L. subtorminosus, and L. speciosus, all of which have a hairy cap edge. Singer's 1986 classification of the Agaricales does not divide subsection Aspideini into stirpes, instead grouping Lactarius repraesentaneus with L. aspideus, L. uvidus
, L. luridis, L. psammicola, and L. speciosus.
The mushroom is commonly
known as the "northern bearded milkcap", the "northern milkcap", or the "purple-staining milkcap". The specific epithet repraesentaneus is Latin
for "well-represented".
of L. repraesentaneus is 6 – wide, convex to broadly funnel-shaped. The margin (the edge of the cap) is conspicuously bearded on young specimens. The cap surface is faintly zoned to azonate, with a thin layer of matted fibers, often becoming scurfy with age. It is dry to somewhat sticky, light yellow to orange-yellow, sometimes with rusty tints when older. The attachment of the gills to the stem is slightly decurrent—running slightly down the length of the stem. The gills are moderately broad, close to crowded, sometimes forked near the stem. Normally a cream to pale ochraceous
color, they will stain dull lilac to purple when bruised.
The stem
is 5 – long, 1 – thick, nearly equal in width throughout or enlarged downward, hollow at maturity, sticky to dry, scrobiculate (coarsely pitted), pale yellow to orange-yellow, and stains dull lilac to purple. The flesh
is firm, brittle, white, and will stain dull lilac to purple when cut. The odor is sometimes faintly fragrant or not distinctive, but when the mushroom is dry it smells intensely of soap. Its taste is mild to slightly acrid or somewhat bitter, and the flavor has been compared to sweet flag (Acorus calamus). The abundant amount of latex
produced by the mushroom is white to cream, unchanging, staining all tissues dull lilac to purple. It tastes mild to slightly acrid or somewhat bitter. The spore print
is yellowish. The fruit bodies are poisonous and consumption will cause stomach aches, but the nature of the toxic agents has not been identified.
The spore
s are 8–12 by 6.5–9 µm
, broadly ellipsoid to ellipsoid, ornamented with warts and ridges that do not form a reticulum, prominences up to 0.8 µm high, hyaline
, and amyloid
. The cap cuticle
is an ixocutis—with the hypha
e embedded in a slimy or gelatinized layer.
Lactarius repraesentaneus is similar in appearance to Lactarius scrobiculatus
, which has latex that turns yellow when exposed to air, a different smell, a stinging flesh and a different reaction of the milk to alkali: in L. scrobiculatus the milk turns reddish-orange while that of L. representaneus does not change color. Lactarius uvidus
also has a violet reaction but it has a different color and is not hairy at the margin of the cap. L. flavidus has a yellowish cap but does not have a hairy margin.
l relationships with trees. This is a mutually beneficial relationship where the hyphae of the fungus grow around the roots of trees, forming a sheath of tissue. This enables the fungus to receive moisture, protection and nutritive byproducts of the tree, and affords the tree greater access to soil nutrients. The fruit bodies of L. repraesentaneus are found scattered or in groups on the ground under spruce
from August to September. The fungus is distributed in higher elevations in the northern USA and southern Canada where spruce is present. It has also been reported from Alaska
, California
, and the Rocky Mountains
. The frequency of its appearance is described as occasional to fairly common. In Europe, where it is fairly rare, it is found mainly underneath sallows (Salix capraea) in forests at the foot of mountains on non-calcareous
soil. It has been collected in Czechoslovakia, Sweden, Switzerland, the French Alps
and England; overall, it is widely distributed throughout the temperate
zone of the northern hemisphere. The fungus has also been collected under birch (B. pubescens, B. nana, and B. glandulosa) in Greenland
.
activity against Staphylococcus aureus
in 1947. The substance responsible for the antibacterial activity, determined to be heat-sensitive, was not identified. A number of chemicals have been isolated and identified from L. repraesentaneus that can regulate the growth of plants. The chemicals, in a class called sesquiterpenoids are named repraesentin A, and two related sesquiterpenes, namely repraesentins B and C. These compounds were shown to promote the radicle
elongation of lettuce seedlings by 136%, 118% and 184% at 67 ppm, respectively. Other compounds reported in 2006 are repraesentins D, E, and F. Repraesentin E showed the strongest growth promotion activity, 164% at 3.6 µm, of the three compounds toward the radicle elongation of lettuce seedlings.
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 Russulaceae
Russulaceae
The Russulaceae are a family of fungi in the order Russulales. According to a 2008 estimate, the family contains 1243 species. Its species typically have fruit bodies with friable, chalk-like stalks, that break with a distinct crack, somewhat like a carrot but with porous flesh...
family. It has a northerly distribution, and is found in temperate
Temperate
In geography, temperate or tepid latitudes of the globe lie between the tropics and the polar circles. The changes in these regions between summer and winter are generally relatively moderate, rather than extreme hot or cold...
regions of North America and Europe, associated with 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...
trees. Distinguishing features of its 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...
include the large orange-yellow 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...
up to 18 cm (7.1 in) wide, cream to pale yellow gills, and a yellow coarsely-pitted 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...
that is up to 12 cm (4.7 in) long and 3 cm (1.2 in) thick. Cut fruit bodies ooze a white latex
Latex
Latex is the stable dispersion of polymer microparticles in an aqueous medium. Latexes may be natural or synthetic.Latex as found in nature is a milky fluid found in 10% of all flowering plants . It is a complex emulsion consisting of proteins, alkaloids, starches, sugars, oils, tannins, resins,...
that will stain mushroom tissue lilac
Lilac (color)
Lilac is a color that is a pale tone of violet that is a representation of the average color of most lilac flowers. It might also be described as light purple. The colors of some lilac flowers may be equivalent to the colors shown below as pale lilac, rich lilac, or deep lilac...
to purple. Several chemicals have been isolated and identified from the fruit bodies that can modify the growth of plants, and the mushroom also has antibiotic
Antibiotic
An antibacterial is a compound or substance that kills or slows down the growth of bacteria.The term is often used synonymously with the term antibiotic; today, however, with increased knowledge of the causative agents of various infectious diseases, antibiotic has come to denote a broader range of...
activity against Staphylococcus aureus
Staphylococcus aureus
Staphylococcus aureus is a facultative anaerobic Gram-positive coccal bacterium. It is frequently found as part of the normal skin flora on the skin and nasal passages. It is estimated that 20% of the human population are long-term carriers of S. aureus. S. aureus is the most common species of...
. L. repraesentaneus is poisonous, and consumption causes stomach aches.
Taxonomy
Lactarius repraesentaneus was first described by German mycologist Max BritzelmayrMax Britzelmayr
Max Britzelmayr was a German mycologist and lichenologist who was a native of Augsburg.He spent his career as a schoolteacher and Kreisschulinspektor in Augsburg...
in 1885, based on material collected from Bavaria
Bavaria
Bavaria, formally the Free State of Bavaria is a state of Germany, located in the southeast of Germany. With an area of , it is the largest state by area, forming almost 20% of the total land area of Germany...
. The variety Lactarius scrobiculatus var. repraesentaneus, proposed by Killermann in 1933, is considered a 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...
. 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....
in 1942 defined the subspecies
Subspecies
Subspecies in biological classification, is either a taxonomic rank subordinate to species, ora taxonomic unit in that rank . A subspecies cannot be recognized in isolation: a species will either be recognized as having no subspecies at all or two or more, never just one...
L. repraesentaneus ssp. speciosus to include fruit bodies with matted fibers ("felt") arranged in concentric rings on the cap (zonate), in comparison with the nominate subspecies, where in young specimens the felt was evenly distributed on the cap surface, only becoming zonate at the cap margins in maturity.
According to the classification proposed by Lexemuel Ray Hesler
Lexemuel Ray Hesler
-External links:* Finding Aid for the Lexemuel Ray Hesler Collection, 1899-1982...
and Alexander H. Smith
Alexander H. Smith
Alexander Hanchett Smith was an American mycologist known for his extensive contributions to the taxonomy and phylogeny of the higher fungi, especially the agarics.-Early life:...
in their 1979 monograph
Monograph
A monograph is a work of writing upon a single subject, usually by a single author.It is often a scholarly essay or learned treatise, and may be released in the manner of a book or journal article. It is by definition a single document that forms a complete text in itself...
of North American Lactarius species, L. repraesentaneus belongs in the stirps Speciosus of the section Aspideini, of the subgenus
Subgenus
In biology, a subgenus is a taxonomic rank directly below genus.In zoology, a subgeneric name can be used independently or included in a species name, in parentheses, placed between the generic name and the specific epithet: e.g. the Tiger Cowry of the Indo-Pacific, Cypraea tigris Linnaeus, which...
Piperites of genus Lactarius
Lactarius
Lactarius is a genus of mushroom-producing fungi. The genus, collectively known commonly as milk-caps, are characterized by the fact that they exude a milky fluid if cut or damaged...
. Other species in stirps Speciosus include L. dispersus, L. subtorminosus, and L. speciosus, all of which have a hairy cap edge. Singer's 1986 classification of the Agaricales does not divide subsection Aspideini into stirpes, instead grouping Lactarius repraesentaneus with L. aspideus, L. uvidus
Lactarius uvidus
Lactarius uvidus is a European and North American "milk-cap" mushroom, of which the milk turns violet when the flesh is damaged. The fungi generally identified as L. uvidus are part of a complex of closely related species and varieties which are difficult to delimit definitively, .It gives its...
, L. luridis, L. psammicola, and L. speciosus.
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 "northern bearded milkcap", the "northern milkcap", or the "purple-staining milkcap". The specific epithet repraesentaneus is 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...
for "well-represented".
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 L. repraesentaneus is 6 – wide, convex to broadly funnel-shaped. The margin (the edge of the cap) is conspicuously bearded on young specimens. The cap surface is faintly zoned to azonate, with a thin layer of matted fibers, often becoming scurfy with age. It is dry to somewhat sticky, light yellow to orange-yellow, sometimes with rusty tints when older. The attachment of the gills to the stem is slightly decurrent—running slightly down the length of the stem. The gills are moderately broad, close to crowded, sometimes forked near the stem. Normally a cream to pale ochraceous
Ochre
Ochre is the term for both a golden-yellow or light yellow brown color and for a form of earth pigment which produces the color. The pigment can also be used to create a reddish tint known as "red ochre". The more rarely used terms "purple ochre" and "brown ochre" also exist for variant hues...
color, they will stain dull lilac to purple when bruised.
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 5 – long, 1 – thick, nearly equal in width throughout or enlarged downward, hollow at maturity, sticky to dry, scrobiculate (coarsely pitted), pale yellow to orange-yellow, and stains dull lilac to purple. 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 firm, brittle, white, and will stain dull lilac to purple when cut. The odor is sometimes faintly fragrant or not distinctive, but when the mushroom is dry it smells intensely of soap. Its taste is mild to slightly acrid or somewhat bitter, and the flavor has been compared to sweet flag (Acorus calamus). The abundant amount of latex
Latex
Latex is the stable dispersion of polymer microparticles in an aqueous medium. Latexes may be natural or synthetic.Latex as found in nature is a milky fluid found in 10% of all flowering plants . It is a complex emulsion consisting of proteins, alkaloids, starches, sugars, oils, tannins, resins,...
produced by the mushroom is white to cream, unchanging, staining all tissues dull lilac to purple. It tastes mild to slightly acrid or somewhat bitter. 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 yellowish. The fruit bodies are poisonous and consumption will cause stomach aches, but the nature of the toxic agents has not been identified.
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 8–12 by 6.5–9 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...
, broadly ellipsoid to ellipsoid, ornamented with warts and ridges that do not form a reticulum, prominences up to 0.8 µm high, 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...
, and amyloid
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...
. The cap cuticle
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 an ixocutis—with 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 embedded in a slimy or gelatinized layer.
Similar species
Lactarius scrobiculatus
Lactarius scrobiculatus is a basidiomycete fungus, belonging to the genus Lactarius, whose members are called "milk caps." Taxonomy places this species into subgenus Piperites, section Zonarii, subsection Scrobiculati....
, which has latex that turns yellow when exposed to air, a different smell, a stinging flesh and a different reaction of the milk to alkali: in L. scrobiculatus the milk turns reddish-orange while that of L. representaneus does not change color. Lactarius uvidus
Lactarius uvidus
Lactarius uvidus is a European and North American "milk-cap" mushroom, of which the milk turns violet when the flesh is damaged. The fungi generally identified as L. uvidus are part of a complex of closely related species and varieties which are difficult to delimit definitively, .It gives its...
also has a violet reaction but it has a different color and is not hairy at the margin of the cap. L. flavidus has a yellowish cap but does not have a hairy margin.
Habitat and distribution
Like other Lactarius species, L. repraesentaneus is thought to form mycorrhizaMycorrhiza
A mycorrhiza is a symbiotic association between a fungus and the roots of a vascular plant....
l relationships with trees. This is a mutually beneficial relationship where the hyphae of the fungus grow around the roots of trees, forming a sheath of tissue. This enables the fungus to receive moisture, protection and nutritive byproducts of the tree, and affords the tree greater access to soil nutrients. The fruit bodies of L. repraesentaneus are found scattered or in groups on the ground under 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...
from August to September. The fungus is distributed in higher elevations in the northern USA and southern Canada where spruce is present. It has also been reported from 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...
, 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 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...
. The frequency of its appearance is described as occasional to fairly common. In Europe, where it is fairly rare, it is found mainly underneath sallows (Salix capraea) in forests at the foot of mountains on non-calcareous
Calcareous
Calcareous is an adjective meaning mostly or partly composed of calcium carbonate, in other words, containing lime or being chalky. The term is used in a wide variety of scientific disciplines.-In zoology:...
soil. It has been collected in Czechoslovakia, Sweden, Switzerland, the French Alps
French Alps
The French Alps are those portions of the Alps mountain range which stand within France, located in the Rhône-Alpes and Provence-Alpes-Côte d'Azur regions....
and England; overall, it is widely distributed throughout the temperate
Temperate
In geography, temperate or tepid latitudes of the globe lie between the tropics and the polar circles. The changes in these regions between summer and winter are generally relatively moderate, rather than extreme hot or cold...
zone of the northern hemisphere. The fungus has also been collected under birch (B. pubescens, B. nana, and B. glandulosa) in Greenland
Greenland
Greenland is an autonomous country within the Kingdom of Denmark, located between the Arctic and Atlantic Oceans, east of the Canadian Arctic Archipelago. Though physiographically a part of the continent of North America, Greenland has been politically and culturally associated with Europe for...
.
Bioactive compounds
Lactarius repraesentaneus was reported to have antibioticAntibiotic
An antibacterial is a compound or substance that kills or slows down the growth of bacteria.The term is often used synonymously with the term antibiotic; today, however, with increased knowledge of the causative agents of various infectious diseases, antibiotic has come to denote a broader range of...
activity against Staphylococcus aureus
Staphylococcus aureus
Staphylococcus aureus is a facultative anaerobic Gram-positive coccal bacterium. It is frequently found as part of the normal skin flora on the skin and nasal passages. It is estimated that 20% of the human population are long-term carriers of S. aureus. S. aureus is the most common species of...
in 1947. The substance responsible for the antibacterial activity, determined to be heat-sensitive, was not identified. A number of chemicals have been isolated and identified from L. repraesentaneus that can regulate the growth of plants. The chemicals, in a class called sesquiterpenoids are named repraesentin A, and two related sesquiterpenes, namely repraesentins B and C. These compounds were shown to promote the radicle
Radicle
In botany, the radicle is the first part of a seedling to emerge from the seed during the process of germination. The radicle is the embryonic root of the plant, and grows downward in the soil...
elongation of lettuce seedlings by 136%, 118% and 184% at 67 ppm, respectively. Other compounds reported in 2006 are repraesentins D, E, and F. Repraesentin E showed the strongest growth promotion activity, 164% at 3.6 µm, of the three compounds toward the radicle elongation of lettuce seedlings.