Lactarius fallax
Encyclopedia
Lactarius fallax, commonly known as the velvety milk cap, is a species of fungus
in the Russulaceae
family. Found in both spruce
and mixed conifer forests, it is a fairly common species in the Pacific Northwest
region of North America, with a northerly range extending to Alaska
. Its fruit bodies
are medium-sized, with velvety, brown to blackish caps
up to 3 – in diameter bearing a distinct pointed umbo
. The caps are supported by velvety stems
up to 6 cm (2.4 in) long and 1.5 cm (0.590551181102362 in) thick. The mushroom oozes a whitish latex
when it is cut, and injured tissue eventually turns a dull reddish color. The eastern North American and European species Lactarius lignyotus
is closely similar in appearance, but can be distinguished by its differing range.
and Lexemuel Ray Hesler
in a 1962 publication. Smith made the initial collection in late October 1944, in Rhododendron, Oregon
. The publication also described the variety Lactarius fallax var. concolor based on specimens collected in Mount Hood
. According to Smith and Hesler, this variety had been to that point generally identified as Lactarius lignyotus in the Pacific Northwest
. They described the variety L. lignyotus var. americanus to account for differences such as "spore ornamentation, distant gills at maturity, and the typically slightly acrid taste". However, in their 1979 monograph
of North American Lactarius species, they considered L. lignyotus var. americanus to be equivalent (and thus synonymous
) to L. fallax var. concolor. The specific epithet fallax is derived from the Latin
word "deceptive". The mushroom is commonly
known as the "velvety milk cap".
Lactarius fallax is classified in the section Plinthogalus of the subgenus
Plinthogalus of the genus Lactarius
. Species in this section have brown to blackish caps, and a cap cuticle
that contains a dissolved brown pigment
. The cuticle of most species is of the trichoderm type—where the outermost hypha
e emerge roughly parallel, like hairs, perpendicular to the cap surface.
of L. fallax is 3 – wide, ranging in shape from convex to nearly flat with a small umbo
, expanding to plane or becoming shallowly depressed, with or without the umbo. The margin (cap edge) is even or scalloped. The cap surface is dry and velvety, finely wrinkled over the center, azonate (without concentric lines), and dark sooty brown to blackish. The gills are attached to subdecurrent (running shortly down the length of the stem), narrow, crowded, not forked, white at first, and become creamy buff with age. The edges of the gills are brown like the cap, and slowly stain vinaceous (wine-colored) when bruised. There are several tiers of lamellulae (short gills that do not reach the stem) interspersed among the full-length gills. The stem
is 2.5 – long, 8 – thick, nearly equal in width throughout, dry, solid, unpolished or velvety, and a paler brown than the cap. The flesh
is thin, brittle, staining pale vinaceous. The odor is not distinctive, and the taste mild or faintly acrid. The latex
is copious, white on exposure, unchanging, slowly staining flesh and gills vinaceous. The spore print
is yellowish. The edibility
of the mushroom has not been officially documented. The species is one of several brown to nearly black milkcaps that are, according to David Arora
, "notable for their beauty, and therefore likely to attract the attention of even the casual collector."
The variety Lactarius fallax var. concolor is nearly identical to the main species in appearance and distribution, but has gill edges that are colored like the gill face.
s are spherical, and ornamented with warts and ridges that form a partial reticulum (a net-like pattern of lines) with prominences up to 2 µm high. They are hyaline
(translucent), amyloid
(meaning they will absord iodine
when stained with Melzer's reagent
), and measure 7.5–10.0 by 7–9.5 µm. The cap cuticle
is a trichoderm. The basidia (the spore-bearing cells) are 38–56 by 10–13 µm, club-shaped, four-spored, and hyaline
when mounted in a dilute solution of potassium hydroxide
(KOH). There are abundant cheilocystidia (cystidia
found on the edge of gills), with contents ranging in color from dingy yellow to hyaline in KOH. They measure 32–50 by 3-6 µm, and are maybe be shaped somewhat like a spindle (tapered on each end) or a cylinder, or they may be flexuous (winding from side to side). The pleurocystidia (cystidia found on the gill face) are filamentous, 2.5–5 µm in diameter, and rare to scattered.
, which prefers to grow near hardwood
s, has close gills.
. Field observations suggest that the fungus can form ectomycorrhizal associations with Tsuga heterophylla. Hesler and Smith noted that the variety concolor was prevalent under species of Fir
.
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. Found in both 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...
and mixed conifer forests, it is a fairly common species in 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...
region of North America, with a northerly range extending 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...
. Its 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 medium-sized, with velvety, brown to blackish 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...
up to 3 – in diameter bearing a distinct pointed umbo
Umbo (mycology)
thumb|right|[[Cantharellula umbonata]] has an umbo.thumb|right|The cap of [[Psilocybe makarorae]] is acutely papillate.An umbo is a raised area in the center of a mushroom cap. Caps that possess this feature are called umbonate. Umbos that are sharply pointed are called acute, while those that are...
. The caps are supported by velvety stems
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...
up to 6 cm (2.4 in) long and 1.5 cm (0.590551181102362 in) thick. The mushroom oozes a whitish 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 it is cut, and injured tissue eventually turns a dull reddish color. The eastern North American and European species Lactarius lignyotus
Lactarius lignyotus
Lactarius lignyotus is a member of the large milk-cap genus Lactarius in the order Russulales. It was first described scientifically by Elias Magnus Fries in 1855....
is closely similar in appearance, but can be distinguished by its differing range.
Taxonomy and classification
The species was originally described by American mycologists Alexander H. SmithAlexander 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:...
and Lexemuel Ray Hesler
Lexemuel Ray Hesler
-External links:* Finding Aid for the Lexemuel Ray Hesler Collection, 1899-1982...
in a 1962 publication. Smith made the initial collection in late October 1944, in Rhododendron, Oregon
Rhododendron, Oregon
Rhododendron is an unincorporated community in Clackamas County, Oregon, United States. It is located within the Mount Hood Corridor, between Government Camp and Zigzag on U.S. Route 26...
. The publication also described the variety Lactarius fallax var. concolor based on specimens collected in Mount Hood
Mount Hood
Mount Hood, called Wy'east by the Multnomah tribe, is a stratovolcano in the Cascade Volcanic Arc of northern Oregon. It was formed by a subduction zone and rests in the Pacific Northwest region of the United States...
. According to Smith and Hesler, this variety had been to that point generally identified as Lactarius lignyotus in 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...
. They described the variety L. lignyotus var. americanus to account for differences such as "spore ornamentation, distant gills at maturity, and the typically slightly acrid taste". However, 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, they considered L. lignyotus var. americanus to be equivalent (and thus synonymous
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...
) to L. fallax var. concolor. The specific epithet fallax is derived from the 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...
word "deceptive". 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 "velvety milk cap".
Lactarius fallax is classified in the section Plinthogalus 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...
Plinthogalus of the 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...
. Species in this section have brown to blackish caps, and a 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....
that contains a dissolved brown 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...
. The cuticle of most species is of the trichoderm type—where the outermost 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 emerge roughly parallel, like hairs, perpendicular to the cap surface.
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. fallax is 3 – wide, ranging in shape from convex to nearly flat with a small umbo
Umbo (mycology)
thumb|right|[[Cantharellula umbonata]] has an umbo.thumb|right|The cap of [[Psilocybe makarorae]] is acutely papillate.An umbo is a raised area in the center of a mushroom cap. Caps that possess this feature are called umbonate. Umbos that are sharply pointed are called acute, while those that are...
, expanding to plane or becoming shallowly depressed, with or without the umbo. The margin (cap edge) is even or scalloped. The cap surface is dry and velvety, finely wrinkled over the center, azonate (without concentric lines), and dark sooty brown to blackish. The gills are attached to subdecurrent (running shortly down the length of the stem), narrow, crowded, not forked, white at first, and become creamy buff with age. The edges of the gills are brown like the cap, and slowly stain vinaceous (wine-colored) when bruised. There are several tiers of lamellulae (short gills that do not reach the stem) interspersed among the full-length gills. 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 2.5 – long, 8 – thick, nearly equal in width throughout, dry, solid, unpolished or velvety, and a paler brown than the cap. 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 thin, brittle, staining pale vinaceous. The odor is not distinctive, and the taste mild or faintly 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 copious, white on exposure, unchanging, slowly staining flesh and gills vinaceous. 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 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 has not been officially documented. The species is one of several brown to nearly black milkcaps that are, according to David Arora
David Arora
David Arora is an American mycologist, naturalist, and writer. He is the author of two popular books on mushroom identification, Mushrooms Demystified and All That the Rain Promises and More.......
, "notable for their beauty, and therefore likely to attract the attention of even the casual collector."
The variety Lactarius fallax var. concolor is nearly identical to the main species in appearance and distribution, but has gill edges that are colored like the gill face.
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 spherical, and ornamented with warts and ridges that form a partial reticulum (a net-like pattern of lines) with prominences up to 2 µm high. They 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), 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 they will absord 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:...
), and measure 7.5–10.0 by 7–9.5 µm. 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 trichoderm. The basidia (the spore-bearing cells) are 38–56 by 10–13 µm, club-shaped, four-spored, and 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...
when mounted in a dilute solution of 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). There are abundant cheilocystidia (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...
found on the edge of gills), with contents ranging in color from dingy yellow to hyaline in KOH. They measure 32–50 by 3-6 µm, and are maybe be shaped somewhat like a spindle (tapered on each end) or a cylinder, or they may be flexuous (winding from side to side). The pleurocystidia (cystidia found on the gill face) are filamentous, 2.5–5 µm in diameter, and rare to scattered.
Similar species
Lactarius lignyotellus and L. lignyotus are similar to L. fallax, and they are all associated with Picea and Abies; examination of microscopic features cannot be used to distinguish between them. L. lignyotus is restricted in distribution to eastern North America and Europe. Lactarius pseudomucidus is another milk cap with a dark brown cap, but it has a smooth (not velvety) and slimy cap and stem. Another brown-capped eastern North American species is L. gerardii; it has distantly spaced white gills that run down the stem. L. fuliginellusLactarius fuliginellus
Lactarius fuliginellus is a species of fungus in the Russulaceae family. Described as a new species in 1962 by American mycologists Alexander H. Smith and Lexemuel Ray Hesler, the mushroom is found in North America....
, which prefers to grow near 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, has close gills.
Habitat and distribution
The fruit bodies of L. fallax grow scattered to grouped together on the ground, or on very rotten conifer logs in alpine areas under standing conifers. They are fairly common, and typically found between August and October. L. fallax is distributed in the western United States and Canada, with the northern range extending to Alaska; the eastern range is bounded on the east by the Great PlainsGreat Plains
The Great Plains are a broad expanse of flat land, much of it covered in prairie, steppe and grassland, which lies west of the Mississippi River and east of the Rocky Mountains in the United States and Canada. This area covers parts of the U.S...
. Field observations suggest that the fungus can form ectomycorrhizal associations with Tsuga heterophylla. Hesler and Smith noted that the variety concolor was prevalent under species of Fir
Fir
Firs are a genus of 48–55 species of evergreen conifers in the family Pinaceae. They are found through much of North and Central America, Europe, Asia, and North Africa, occurring in mountains over most of the range...
.