Lactarius pubescens
Encyclopedia
Lactarius pubescens, commonly known as the downy milk cap, is a species of fungus
in the Russulaceae
family. It is a medium to large agaric
with a creamy-buff, hairy cap
, whitish gills and short stout stem
. The fungus has a cosmopolitan distribution
, and grows solitarily or in scattered groups on sandy soil under or near birch
.
as Agaricus pubescens in 1794. Elias Magnus Fries
gave it its current name in 1838. The species has also been treated as a variety of Lactarius controversus (as L. controversus var. pubescens by Gillet in 1876) and as both a subspecies
(as Lactarius torminosus subsp. pubescens by Paul Konrad and André Maublanc in 1935) and a variety (as L. torminosus var. pubescens by Lundell in 1956) of Lactarius torminosus
.
Lactarius pubescens is classified in the section Piperites, subsection Piperites. This includes related Lactarius species characterized by having a latex that does not become yellow upon exposure to air, and which does not stain freshly cut surfaces of the fruit body yellow. Based on phylogenetic analysis published in 2004, L. pubescens is most closely related to L. scoticus and L. tesquorum.
The mushroom is commonly
known as the "downy milkcap". The specific epithet pubescens is derived from Latin
, and means "becoming downy".
is 2.5 – wide, obtuse to convex, becoming broadly convex with a depressed center. The margin (cap edge) is rolled inward and bearded with coarse white hairs when young. The cap surface is dry and fibrillose except for the center, which is sticky and smooth when fresh, azonate, white to cream, becoming reddish-orange to vinaceous (wine-colored) on the disc with age. The gills are attached to slightly decurrent, crowded, seldom forked, whitish to pale yellow with pinkish tinges, slowly staining brownish ochraceous when bruised. The stem
is 2 – long, 6 – thick, nearly equal or tapered downward, silky, becoming hollow with age, whitish when young, becoming ochraceous from the base up when older, apex usually tinged pinkish, often with a white basal mycelium. The flesh
is firm, white; odor faintly like geraniums or sometimes pungent, taste acrid. The latex
is white upon exposure, unchanging, not staining tissues, taste acrid. The spore print
is cream with a pinkish tint. The edibility
of Lactarius pubescens has been described as unknown or edible.
The spore
s are 6–8.5 by 5–6.5 µm
, elliptic, ornamented with warts and ridges that sometimes form a partial reticulum, prominences up to 1.5 µm high, hyaline
(translucent), and amyloid
. The cap cuticle
is a layer of thin-walled hypha
e.
has been grown in pure culture and described scientifically.
mimic of L. pubescens, growing in arctic-alpine birch. L. pubescens is often mistaken for L. torminosus which has larger spores (7–10 by 6–8 µm).
and other hardwood
s from August to October. The fungus has been reported from eastern North America, the Pacific Northwest
, Arizona
, California
, Colorado
, Idaho
, and western Canada; its frequency of appearance is occasional. It is also found in Greenland, and was reported for the first time in Rome, Italy, in 1997.
aldehyde lactaral have been isolated from the fruit bodies of L. pubescens.
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 is a medium to large agaric
Agaric
An agaric is a type of fungal fruiting body characterized by the presence of a pileus that is clearly differentiated from the stipe , with lamellae on the underside of the pileus. "Agaric" can also refer to a basidiomycete species characterized by an agaric-type fruiting body...
with a creamy-buff, hairy 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...
, whitish gills and short stout 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...
. The fungus has a cosmopolitan distribution
Cosmopolitan distribution
In biogeography, a taxon is said to have a cosmopolitan distribution if its range extends across all or most of the world in appropriate habitats. For instance, the killer whale has a cosmopolitan distribution, extending over most of the world's oceans. Other examples include humans, the lichen...
, and grows solitarily or in scattered groups on sandy soil under or near birch
Birch
Birch is a tree or shrub of the genus Betula , in the family Betulaceae, closely related to the beech/oak family, Fagaceae. The Betula genus contains 30–60 known taxa...
.
Taxonomy and phylogeny
The species was first named by German botanist Heinrich SchraderHeinrich Schrader (botanist)
Heinrich Adolf Schrader was a German botanist and mycologist. He studied medicine early in life. He named the Australian plant genus Hakea in 1797.Schrader was elected a corresponding member of the Royal Swedish Academy of Sciences in 1815....
as Agaricus pubescens in 1794. Elias Magnus Fries
Elias Magnus Fries
-External links:*, Authors of fungal names, Mushroom, the Journal of Wild Mushrooming.*...
gave it its current name in 1838. The species has also been treated as a variety of Lactarius controversus (as L. controversus var. pubescens by Gillet in 1876) and as both a 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...
(as Lactarius torminosus subsp. pubescens by Paul Konrad and André Maublanc in 1935) and a variety (as L. torminosus var. pubescens by Lundell in 1956) of Lactarius torminosus
Lactarius torminosus
Lactarius torminosus, commonly known as the woolly milkcap or the bearded milkcap, is a large basidiomycete fungus in the genus Lactarius. It is found in the United Kingdom, Northern Europe, and is common in North America, where it grows in mixed forests in a mycorrhizal association with various...
.
Lactarius pubescens is classified in the section Piperites, subsection Piperites. This includes related Lactarius species characterized by having a latex that does not become yellow upon exposure to air, and which does not stain freshly cut surfaces of the fruit body yellow. Based on phylogenetic analysis published in 2004, L. pubescens is most closely related to L. scoticus and L. tesquorum.
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 "downy milkcap". The specific epithet pubescens is derived from 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...
, and means "becoming downy".
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 2.5 – wide, obtuse to convex, becoming broadly convex with a depressed center. The margin (cap edge) is rolled inward and bearded with coarse white hairs when young. The cap surface is dry and fibrillose except for the center, which is sticky and smooth when fresh, azonate, white to cream, becoming reddish-orange to vinaceous (wine-colored) on the disc with age. The gills are attached to slightly decurrent, crowded, seldom forked, whitish to pale yellow with pinkish tinges, slowly staining brownish ochraceous 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 2 – long, 6 – thick, nearly equal or tapered downward, silky, becoming hollow with age, whitish when young, becoming ochraceous from the base up when older, apex usually tinged pinkish, often with a white basal mycelium. 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, white; odor faintly like geraniums or sometimes pungent, taste 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 white upon exposure, unchanging, not staining tissues, taste acrid. 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 cream with a pinkish tint. 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 Lactarius pubescens has been described as unknown or edible.
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 6–8.5 by 5–6.5 µm
Micrometre
A micrometer , is by definition 1×10-6 of a meter .In plain English, it means one-millionth of a meter . Its unit symbol in the International System of Units is μm...
, elliptic, ornamented with warts and ridges that sometimes form a partial reticulum, prominences up to 1.5 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...
(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...
. 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 a layer of thin-walled 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.
Varieties
- Lactarius pubescens var. betulae (A.H. Sm.) Hesler & A.H. Sm. 1979
- Lactarius pubescens var. betularum (Bon) Bon 1985
- Lactarius pubescens var. scoticus (Berk. & Broome) Krieglst. 1991
Ectomycorrhizae
The ectomycorrhizae that L. pubescens forms in association with Betula pendula and Populus tremuloidesPopulus tremuloides
Populus tremuloides is a deciduous tree native to cooler areas of North America, commonly called quaking aspen, trembling aspen, American aspen, and Quakies,. The trees have tall trunks, up to 25 metres, with smooth pale bark, scarred with black. The glossy green leaves, dull beneath, become golden...
has been grown in pure culture and described scientifically.
Similar species
Lactarius scoticus Berk. & Broome is a small morphologicalMorphology (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....
mimic of L. pubescens, growing in arctic-alpine birch. L. pubescens is often mistaken for L. torminosus which has larger spores (7–10 by 6–8 µm).
Habitat and distribution
The fruit bodies of L. pubescens are found scattered or in groups on the ground in wet areas under birchBirch
Birch is a tree or shrub of the genus Betula , in the family Betulaceae, closely related to the beech/oak family, Fagaceae. The Betula genus contains 30–60 known taxa...
and other hardwood
Hardwood
Hardwood is wood from angiosperm trees . It may also be used for those trees themselves: these are usually broad-leaved; in temperate and boreal latitudes they are mostly deciduous, but in tropics and subtropics mostly evergreen.Hardwood contrasts with softwood...
s from August to October. The fungus has been reported from eastern North America, the Pacific Northwest
Pacific Northwest
The Pacific Northwest is a region in northwestern North America, bounded by the Pacific Ocean to the west and, loosely, by the Rocky Mountains on the east. Definitions of the region vary and there is no commonly agreed upon boundary, even among Pacific Northwesterners. A common concept of the...
, Arizona
Arizona
Arizona ; is a state located in the southwestern region of the United States. It is also part of the western United States and the mountain west. The capital and largest city is Phoenix...
, 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...
, Colorado
Colorado
Colorado is a U.S. state that encompasses much of the Rocky Mountains as well as the northeastern portion of the Colorado Plateau and the western edge of the Great Plains...
, Idaho
Idaho
Idaho is a state in the Rocky Mountain area of the United States. The state's largest city and capital is Boise. Residents are called "Idahoans". Idaho was admitted to the Union on July 3, 1890, as the 43rd state....
, and western Canada; its frequency of appearance is occasional. It is also found in Greenland, and was reported for the first time in Rome, Italy, in 1997.
Bioactive compounds
The marasmane sesquiterpenoid pubescenone and the sesquiterpeneSesquiterpene
Sesquiterpenes are a class of terpenes that consist of three isoprene units and have the molecular formula C15H24. Like monoterpenes, sesquiterpenes may be acyclic or contain rings, including many unique combinations...
aldehyde lactaral have been isolated from the fruit bodies of L. pubescens.
External links
- Mushroom Observer Images