Lactarius argillaceifolius
Encyclopedia
Lactarius argillaceifolius is a species of fungus
in the Russulaceae
family. The mushrooms produced by the fungus have convex to flattened drab lilac
-colored caps
that are up to 18 cm (7.1 in) wide. The cream-colored gills are closely spaced together and extend slightly down the length of the stem
, which is up to 9 cm (3.5 in) long by 3.5 cm (1.4 in) thick. The mushroom produces an off-white latex
when injured that stains the mushroom tissue brownish.
The species is found in eastern North America, with a range extending from Canada to northeastern Mexico. It has also been found in pine plantations in Brazil, where it is probably an introduced species
. Lactarius trivialis is a European counterpart that is similar in appearance. In addition to its distribution, it can be distinguished from L. argillaceifolius by differences in preferred habitat and color differences in the gills, cap, and latex. The L. argillaceifolius variety
megacarpus, a larger form with caps up to 27 cm (10.6 in) wide, occurs under coast live oak
and tanoak
in the Pacific Coast
states and Baja California
. Variety dissimilis, described on the basis of a single specimen from South Carolina
, differs from the main form in the microscopic structure of the cap cuticle
.
and Alexander H. Smith
in their 1979 monograph
on the North American species of Lactarius. The type specimen—collected by Smith from Oak Grove, Livingston County, Michigan, in July of 1972—is housed at the herbarium
of the University of Michigan
. Hesler and Smith simultaneously published the varieties dissimilis and megacarpus, collected from South Carolina
and California
, respectively. The variety megacarpus is commonly
known as the "vulgar milkcap".
Smith and Hesler classified L. argillaceifolius in subgenus
Tristes, in stirps Argillaceifolius. This grouping of related species, which includes L. fumaecolor, is characterized by the gelatinous cuticle of the stem.
is 4 – wide, and initially convex to broadly convex before flattening out with a depressed center. The cap margin is curved inward, and often remains that way into maturity. The cap surface is covered with fine soft hairs when young, but later becomes smooth; it is slimy and sticky when wet. The color of the cap ranges from lilac
-brown when young, fading to lilac-tan
or pale lilac-gray and eventually to pale tan or pinkish-buff at the center. The gills are attached to slightly decurrent (extending somewhat down the length of the stem), broad, and packed together closely. They are cream-colored when young, and later develop pinkish tones near the margin. In maturity, they become flushed with brownish-orange. The color stains buff to olive-brown to dark brown when bruised.
The stem
is 6 – long by 1.5 – thick, and nearly equal in width throughout or tapering downward. Its surface may be slimy or dry, depending on the moisture in the environment. It is whitish, but in age becomes spotted with brownish stains. The flesh
is firm, and white to buff. Its odor is not distinctive, while its taste is mild or slowly becomes slightly acrid. The latex
is creamy-white on initial exposure, and stains the gills grayish-brown to dark brown or olive-brown; its taste is mild or slowly becomes slightly acrid. Older fruit bodies tend to have less abundant and weaker-tasting latex. The spore print
is pinkish-buff. The edibility of L. argillaceifolius is unknown. The cap surface will turn yellow to orange when a drop of dilute potassium hydroxide
is applied.
s are roughly spherical to broadly elliptical, and measure 7–11 by 7–8 µm
. They are ornamented with warts and ridges that sometimes form a partial reticulum (a pattern of interconnected ridges), with prominences up to 1 µm high. The spore are hyaline
(translucent) and amyloid
, meaning that they will absorb iodine
when stained with Melzer's reagent
. The cap cuticle
of young specimens is made of a tissue type known an ixotrichoderm, which contains gelatinized hypha
e of different lengths arranged in roughly parallel fashion. As the mushroom matures, the cap cuticle gradually becomes an ixolattice—characterized by branching, entangled, gelatinous hyphae. The basidia
(the spore-bearing cells) are four-spored, and measure 45–52 by 9–10.5 µm. The pleurocystidia (cystidia on the gill face) are abundant, and relatively long—between 60–140 µm long by 6–14 µm thick. The cheilocystidia (cystidia on the gill edge) measure 32–67 by 6–9 µm.
, is nearly identical in appearance, but it has white latex that tastes bitter then acrid. The structure of the cap cuticle
differs from the nominate variety in that it has dextrinoid (staining yellowish or reddish brown with Meltzer's reagent) incrustations on the hyphae. The variety megacarpus has a larger cap (up to 27 cm (10.6 in) wide with flesh that is up to 3 cm (1.2 in) thick), and white and unchanging latex with an acrid taste. Its stem measures 16 to 20 cm (6.3 to 7.9 in) long by 4 to 5 cm (1.6 to 2 in) wide near the top. Microscopically, the spores of var. megacarpus are more reticulate than the nominate variety.
species, L. argillaceifolius is mycorrhiza
l. The fruit bodies of Lactarius argillaceifolius grow scattered or in groups on the ground under hardwoods, especially oak
, from July to October. It is often one of the first mycorrhizal mushrooms to fruit in forests dominated by oak and hickory. The fruit bodies are slow to develop and are long-lasting. The species is found from eastern Canada south to Florida
, and west to Minnesota
and Texas
. It is common in northeast Mexico. The mushroom has also been reported from southern Brazil (state of Santa Catarina
) growing in association with pine (Pinus elliottii) plantations, where it has probably been introduced
with pine seedlings brought by settlers. L. argillaceifolius var. megacarpus has been collected from Baja California
, California, Oregon, and Washington, where it grows in association with coast live oak
and tanoak
.
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. The mushrooms produced by the fungus have convex to flattened drab 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...
-colored 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...
that are up to 18 cm (7.1 in) wide. The cream-colored gills are closely spaced together and extend slightly down the length 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...
, which is up to 9 cm (3.5 in) long by 3.5 cm (1.4 in) thick. The mushroom produces an off-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,...
when injured that stains the mushroom tissue brownish.
The species is found in eastern North America, with a range extending from Canada to northeastern Mexico. It has also been found in pine plantations in Brazil, where it is probably an introduced species
Introduced species
An introduced species — or neozoon, alien, exotic, non-indigenous, or non-native species, or simply an introduction, is a species living outside its indigenous or native distributional range, and has arrived in an ecosystem or plant community by human activity, either deliberate or accidental...
. Lactarius trivialis is a European counterpart that is similar in appearance. In addition to its distribution, it can be distinguished from L. argillaceifolius by differences in preferred habitat and color differences in the gills, cap, and latex. The L. argillaceifolius variety
Variety (biology)
In botanical nomenclature, variety is a taxonomic rank below that of species: as such, it gets a three-part infraspecific name....
megacarpus, a larger form with caps up to 27 cm (10.6 in) wide, occurs under coast live oak
Coast Live Oak
Quercus agrifolia, the Coast Live Oak, is an evergreen oak , native to the California Floristic Province. It grows west of the Sierra Nevada from Mendocino County, California, south to northern Baja California in Mexico. It is classified in the red oak section Quercus agrifolia, the Coast Live Oak,...
and tanoak
Tanoak
Tanoak, formerly known taxonomically as Lithocarpus densiflorus, was recently moved into a new genus, Notholithocarpus, based on multiple lines of evidence....
in 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...
states and Baja California
Baja California
Baja California officially Estado Libre y Soberano de Baja California is one of the 31 states which, with the Federal District, comprise the 32 Federal Entities of Mexico. It is both the northernmost and westernmost state of Mexico. Before becoming a state in 1953, the area was known as the North...
. Variety dissimilis, described on the basis of a single specimen from South Carolina
South Carolina
South Carolina is a state in the Deep South of the United States that borders Georgia to the south, North Carolina to the north, and the Atlantic Ocean to the east. Originally part of the Province of Carolina, the Province of South Carolina was one of the 13 colonies that declared independence...
, differs from the main form in the microscopic structure of 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....
.
Taxonomy and classification
The species was first described by American mycologists Lexemuel Ray HeslerLexemuel 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...
on the North American species of Lactarius. The type specimen—collected by Smith from Oak Grove, Livingston County, Michigan, in July of 1972—is housed at the herbarium
Herbarium
In botany, a herbarium – sometimes known by the Anglicized term herbar – is a collection of preserved plant specimens. These specimens may be whole plants or plant parts: these will usually be in a dried form, mounted on a sheet, but depending upon the material may also be kept in...
of the University of Michigan
University of Michigan
The University of Michigan is a public research university located in Ann Arbor, Michigan in the United States. It is the state's oldest university and the flagship campus of the University of Michigan...
. Hesler and Smith simultaneously published the varieties dissimilis and megacarpus, collected from South Carolina
South Carolina
South Carolina is a state in the Deep South of the United States that borders Georgia to the south, North Carolina to the north, and the Atlantic Ocean to the east. Originally part of the Province of Carolina, the Province of South Carolina was one of the 13 colonies that declared independence...
and 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...
, respectively. The variety megacarpus 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 "vulgar milkcap".
Smith and Hesler classified L. argillaceifolius in 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...
Tristes, in stirps Argillaceifolius. This grouping of related species, which includes L. fumaecolor, is characterized by the gelatinous cuticle of the stem.
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...
is 4 – wide, and initially convex to broadly convex before flattening out with a depressed center. The cap margin is curved inward, and often remains that way into maturity. The cap surface is covered with fine soft hairs when young, but later becomes smooth; it is slimy and sticky when wet. The color of the cap ranges from 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...
-brown when young, fading to lilac-tan
Tan (color)
Tan is a pale whiteish, tawny shade of white. The name is derived from tannum used in the tanning of leather.The first recorded use of tan as a shade name in English was in the year 1590....
or pale lilac-gray and eventually to pale tan or pinkish-buff at the center. The gills are attached to slightly decurrent (extending somewhat down the length of the stem), broad, and packed together closely. They are cream-colored when young, and later develop pinkish tones near the margin. In maturity, they become flushed with brownish-orange. The color stains buff to olive-brown to dark brown 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 6 – long by 1.5 – thick, and nearly equal in width throughout or tapering downward. Its surface may be slimy or dry, depending on the moisture in the environment. It is whitish, but in age becomes spotted with brownish stains. 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, and white to buff. Its odor is not distinctive, while its taste is mild or slowly becomes slightly acrid. The 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,...
is creamy-white on initial exposure, and stains the gills grayish-brown to dark brown or olive-brown; its taste is mild or slowly becomes slightly acrid. Older fruit bodies tend to have less abundant and weaker-tasting latex. 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 pinkish-buff. The edibility of L. argillaceifolius is unknown. The cap surface will turn yellow to orange when 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...
is applied.
Microscopic characteristics
The sporeSpore
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 roughly spherical to broadly elliptical, and measure 7–11 by 7–8 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 are ornamented with warts and ridges that sometimes form a partial reticulum (a pattern of interconnected ridges), with prominences up to 1 µm high. The spore are 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) 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...
, meaning that they will absorb iodine
Iodine
Iodine is a chemical element with the symbol I and atomic number 53. The name is pronounced , , or . The name is from the , meaning violet or purple, due to the color of elemental iodine vapor....
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:...
. 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....
of young specimens is made of a tissue type known an ixotrichoderm, which contains gelatinized 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 of different lengths arranged in roughly parallel fashion. As the mushroom matures, the cap cuticle gradually becomes an ixolattice—characterized by branching, entangled, gelatinous hyphae. The basidia
Basidium
thumb|right|500px|Schematic showing a basidiomycete mushroom, gill structure, and spore-bearing basidia on the gill margins.A basidium is a microscopic, spore-producing structure found on the hymenophore of fruiting bodies of basidiomycete fungi. The presence of basidia is one of the main...
(the spore-bearing cells) are four-spored, and measure 45–52 by 9–10.5 µm. The pleurocystidia (cystidia on the gill face) are abundant, and relatively long—between 60–140 µm long by 6–14 µm thick. The cheilocystidia (cystidia on the gill edge) measure 32–67 by 6–9 µm.
Varieties
Lactarius argillaceifolius var. dissimilis, a variety reported from South CarolinaSouth Carolina
South Carolina is a state in the Deep South of the United States that borders Georgia to the south, North Carolina to the north, and the Atlantic Ocean to the east. Originally part of the Province of Carolina, the Province of South Carolina was one of the 13 colonies that declared independence...
, is nearly identical in appearance, but it has white latex that tastes bitter then acrid. The structure of 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....
differs from the nominate variety in that it has dextrinoid (staining yellowish or reddish brown with Meltzer's reagent) incrustations on the hyphae. The variety megacarpus has a larger cap (up to 27 cm (10.6 in) wide with flesh that is up to 3 cm (1.2 in) thick), and white and unchanging latex with an acrid taste. Its stem measures 16 to 20 cm (6.3 to 7.9 in) long by 4 to 5 cm (1.6 to 2 in) wide near the top. Microscopically, the spores of var. megacarpus are more reticulate than the nominate variety.
Similar species
Lactarius trivialis is a European species that is similar in appearance to L. argillaceifolius, and they are often confused for each other. L. trivialis can be distinguished by gills that stain brown when exposed to the latex, and a preference for growing in conifer- and birch-rich boreal and subalpine forests. Variety megacarpus may be confused with L. pallescens, a smaller paler-colored species with latex that stains gills lilac rather than brown.Habitat and distribution
Like all LactariusLactarius
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...
species, L. argillaceifolius is mycorrhiza
Mycorrhiza
A mycorrhiza is a symbiotic association between a fungus and the roots of a vascular plant....
l. The fruit bodies of Lactarius argillaceifolius grow scattered or in groups on the ground under hardwoods, especially 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...
, from July to October. It is often one of the first mycorrhizal mushrooms to fruit in forests dominated by oak and hickory. The fruit bodies are slow to develop and are long-lasting. The species is found from eastern Canada south to Florida
Florida
Florida is a state in the southeastern United States, located on the nation's Atlantic and Gulf coasts. It is bordered to the west by the Gulf of Mexico, to the north by Alabama and Georgia and to the east by the Atlantic Ocean. With a population of 18,801,310 as measured by the 2010 census, it...
, and west to Minnesota
Minnesota
Minnesota is a U.S. state located in the Midwestern United States. The twelfth largest state of the U.S., it is the twenty-first most populous, with 5.3 million residents. Minnesota was carved out of the eastern half of the Minnesota Territory and admitted to the Union as the thirty-second state...
and Texas
Texas
Texas is the second largest U.S. state by both area and population, and the largest state by area in the contiguous United States.The name, based on the Caddo word "Tejas" meaning "friends" or "allies", was applied by the Spanish to the Caddo themselves and to the region of their settlement in...
. It is common in northeast Mexico. The mushroom has also been reported from southern Brazil (state of Santa Catarina
Santa Catarina (state)
Santa Catarina is a state in southern Brazil with one of the highest standards of living in Latin America. Its capital is Florianópolis, which mostly lies on the Santa Catarina Island. Neighbouring states are Rio Grande do Sul to the south and Paraná to the north. It is bounded on the east by...
) growing in association with pine (Pinus elliottii) plantations, where it has probably been introduced
Introduced species
An introduced species — or neozoon, alien, exotic, non-indigenous, or non-native species, or simply an introduction, is a species living outside its indigenous or native distributional range, and has arrived in an ecosystem or plant community by human activity, either deliberate or accidental...
with pine seedlings brought by settlers. L. argillaceifolius var. megacarpus has been collected from Baja California
Baja California
Baja California officially Estado Libre y Soberano de Baja California is one of the 31 states which, with the Federal District, comprise the 32 Federal Entities of Mexico. It is both the northernmost and westernmost state of Mexico. Before becoming a state in 1953, the area was known as the North...
, California, Oregon, and Washington, where it grows in association with coast live oak
Coast Live Oak
Quercus agrifolia, the Coast Live Oak, is an evergreen oak , native to the California Floristic Province. It grows west of the Sierra Nevada from Mendocino County, California, south to northern Baja California in Mexico. It is classified in the red oak section Quercus agrifolia, the Coast Live Oak,...
and tanoak
Tanoak
Tanoak, formerly known taxonomically as Lithocarpus densiflorus, was recently moved into a new genus, Notholithocarpus, based on multiple lines of evidence....
.