Hygrophorus agathosmus
Encyclopedia
Hygrophorus agathosmus, commonly known as the gray almond waxy cap or the almond woodwax, is a species
of fungus
in the Hygrophoraceae
family. It was first described by Elias Magnus Fries
in 1815; Fries gave it its current name in 1838. A widespread species, it is distributed in the United States, Europe, Africa, and India, and can be found growing under spruce
and pine
in mixed forests
. The fruit bodies
are characterized by a light grayish cap
that measures up to 8 cm (3.1 in) in diameter, waxy gills, a dry stem
, and the distinct odor of bitter almond
s. An edible
but bland-tasting mushroom, extracts of the fruit bodies have been shown in laboratory tests to have antimicrobial
activity against various bacteria that are pathogen
ic to humans.
named the species Agaricus cerasinus in 1836, although he too would later transfer the species to Hygrophorus in 1860. In 1948, Richard Dennis examined the type material, and concluded that the two names referred to the same species. Additional historical synonyms
include Limacium pustulatum var. agathosmum (Kummer
, 1871), and Limacium agathosmum (Wünsch, 1877).
In their 1963 monograph
of the Hygrophorus of North America, American mycologists Lexemuel Ray Hesler
and Alexander H. Smith
classified H. agathosmus in the subsection Camarophylli, a grouping of related species characterized by a dry stem, and the absence of a gelatinous outer veil
.
The specific epithet agathosmus is derived from the Greek
word agathos meaning “good”, and osme meaning “scent”. Hygrophorus agathosmus is commonly
known as the gray almond waxy cap, or the almond woodwax.
is 4 – in diameter, and initially convex with the edges rolled inwards. As it ages and the cap expands, it becomes flat, sometimes with the center slightly depressed, or sometimes with a slight central elevation. The color is a dull ashy gray, and when moist, the cap surface is sticky or tacky to the touch. It is smooth, although the edges can have a layer of minute, soft hairs. The flesh
is soft, and whitish or watery gray. Hygrophorus agathosmus has a pronounced fragrant odor resembling cherry pits or bitter almonds (occasionally the odor is weak).
The gills have an adnate attachment to the stem, but in maturity the attachment becomes adnate-decurrent, meaning the gills start to extend down the length of the stem. The gills are white, but become grayish in maturity, close to distant (40–50 reach the stem), moderately narrow, rather thin. The stem
is 4 – long by 0.6 – thick, whitish at first, and colored pale ashy in age. It is the same thickness throughout or somewhat narrowed toward the base. It is solid, dry or moist but has no gelatinous universal veil
present. When young, the stem surface is evenly covered with tiny fibrils and a fine whitish powder; over time it loses the hairs and the powder and becomes smooth.
, the spores appear to be white. Viewed with a light microscope, the basidiospore
s are 8–10.5 by 4.5–5.5 µm, ellipsoid, smooth, and yellowish in Melzer's reagent
. The spore-bearing cells, the basidia, are four-spored and measure 48–65 long by 6–8 µm thick. Pleurocystidia and cheilocystidia (specialized cystidia found on the gill faces and edges, respectively) are absent in this species. The pileipellis
(cap cuticle) is made of a broad (175–350 µm) gelatinous zone, composed of loosely interwoven, slender (1.5–4 µm) hyphae; the surface hypha
e are a fuscous—a dark brownish-gray color. This hyphal arrangement is called an ixocutis, in which the hyphal walls swell up and gelatinize, giving a translucence to the layer that stands out in contrast to the underlying flesh. The layer of gelatizined hyphae is tenacious, and may be peeled off the cap as a film. Although clamp connection
s are found on the hyphae that make up the flesh of the gill, none are found in the cap flesh nor in the pileipellis.
, but considered bland. A study of the antioxidant
capacity of the mushroom was composed of at least five organic acid
s: oxalic
, citric
, malic
, quinic, and fumaric acid
s. Using a standard laboratory test to determine antimicrobial activity, Hygrophorus agathosmus was shown to inhibit the growth of various pathogen
ic bacteria, including Escherichia coli
, Enterobacter aerogenes
, Salmonella typhimurium, Pseudomonas aeruginosa
, Staphylococcus aureus
, Staphylococcus epidermidis
, and Bacillus subtilis
; it also inhibits the growth of the yeast Candida albicans
and Saccharomyces cerevisiae
.
, has a sticky stem and less pronounced almond odor. Hygrophorus marzuolus
is also similar in appearance, but it lacks a distinctive odor, and has smaller spores than H. agathamosus.
tion of planting stock in forest nurseries. Fruiting bodies are found scattered under spruce
and pine
and in mixed woods
in the United States. The fungus is also found in Europe (Czech Republic, Poland, Russia, Turkey, and the United Kingdom), Africa, and India.
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...
of fungus
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 Hygrophoraceae
Hygrophoraceae
The Hygrophoraceae are a family of fungi in the order Agaricales. Originally conceived as containing white-spored, thick-gilled agarics , including Hygrophorus and Hygrocybe species , DNA evidence has extended the limits of the family, so that it now contains not only agarics but also...
family. It was first described by Elias Magnus Fries
Elias Magnus Fries
-External links:*, Authors of fungal names, Mushroom, the Journal of Wild Mushrooming.*...
in 1815; Fries gave it its current name in 1838. A widespread species, it is distributed in the United States, Europe, Africa, and India, and can be found growing 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...
and pine
Pine
Pines are trees in the genus Pinus ,in the family Pinaceae. They make up the monotypic subfamily Pinoideae. There are about 115 species of pine, although different authorities accept between 105 and 125 species.-Etymology:...
in mixed forests
Temperate broadleaf and mixed forests
Mixed forests are a temperate and humid biome. The typical structure of these forests includes four layers. The uppermost layer is the canopy composed of tall mature trees ranging from 33 to 66 m high. Below the canopy is the three-layered, shade-tolerant understory that is roughly 9 to...
. 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...
are characterized by a light grayish 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...
that measures up to 8 cm (3.1 in) in diameter, waxy gills, a dry 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...
, and the distinct odor of bitter 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...
s. An edible
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...
but bland-tasting mushroom, extracts of the fruit bodies have been shown in laboratory tests to have antimicrobial
Antimicrobial
An anti-microbial is a substance that kills or inhibits the growth of microorganisms such as bacteria, fungi, or protozoans. Antimicrobial drugs either kill microbes or prevent the growth of microbes...
activity against various bacteria that are pathogen
Pathogen
A pathogen gignomai "I give birth to") or infectious agent — colloquially, a germ — is a microbe or microorganism such as a virus, bacterium, prion, or fungus that causes disease in its animal or plant host...
ic to humans.
Taxonomy, classification, and naming
The species was originally named Agaricus agathosmus by Swedish mycologist Elias Fries in 1815; he later moved it into the genus Hygrophorus in 1838. In the interim, English naturalist Miles Joseph BerkeleyMiles Joseph Berkeley
Miles Joseph Berkeley was an English cryptogamist and clergyman, and one of the founders of the science of plant pathology....
named the species Agaricus cerasinus in 1836, although he too would later transfer the species to Hygrophorus in 1860. In 1948, Richard Dennis examined the type material, and concluded that the two names referred to the same species. Additional historical synonyms
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...
include Limacium pustulatum var. agathosmum (Kummer
Paul Kummer
Paul Kummer was a priest, teacher, and scientist in Zerbst, Germany, known chiefly for his contribution to mycological nomenclature. Earlier classification of agarics by pioneering fungal taxonomist Elias Magnus Fries designated only a very small number of genera, with most species falling into...
, 1871), and Limacium agathosmum (Wünsch, 1877).
In their 1963 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 the Hygrophorus of North America, American mycologists 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:...
classified H. agathosmus in the subsection Camarophylli, a grouping of related species characterized by a dry stem, and the absence of a gelatinous outer veil
Partial veil
thumb|150px|right|Developmental stages of [[Agaricus campestris]] showing the role and evolution of a partial veilPartial veil is a mycological term used to describe a temporary structure of tissue found on the fruiting bodies of some basidiomycete fungi, typically agarics...
.
The specific epithet agathosmus is derived from the Greek
Greek language
Greek is an independent branch of the Indo-European family of languages. Native to the southern Balkans, it has the longest documented history of any Indo-European language, spanning 34 centuries of written records. Its writing system has been the Greek alphabet for the majority of its history;...
word agathos meaning “good”, and osme meaning “scent”. Hygrophorus agathosmus 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 gray almond waxy cap, or the almond woodwax.
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 – in diameter, and initially convex with the edges rolled inwards. As it ages and the cap expands, it becomes flat, sometimes with the center slightly depressed, or sometimes with a slight central elevation. The color is a dull ashy gray, and when moist, the cap surface is sticky or tacky to the touch. It is smooth, although the edges can have a layer of minute, soft hairs. 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 soft, and whitish or watery gray. Hygrophorus agathosmus has a pronounced fragrant odor resembling cherry pits or bitter almonds (occasionally the odor is weak).
The gills have an adnate attachment to the stem, but in maturity the attachment becomes adnate-decurrent, meaning the gills start to extend down the length of the stem. The gills are white, but become grayish in maturity, close to distant (40–50 reach the stem), moderately narrow, rather thin. 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 4 – long by 0.6 – thick, whitish at first, and colored pale ashy in age. It is the same thickness throughout or somewhat narrowed toward the base. It is solid, dry or moist but has no gelatinous universal veil
Universal veil
In mycology, a universal veil is a temporary membranous tissue that fully envelops immature fruiting bodies of certain gilled mushrooms. The developing Caesar's mushroom , for example, which may resemble a small white sphere at this point, is protected by this structure...
present. When young, the stem surface is evenly covered with tiny fibrils and a fine whitish powder; over time it loses the hairs and the powder and becomes smooth.
Microscopic characteristics
When viewed in mass, such as with a 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 appear to be white. Viewed with a light microscope, the basidiospore
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...
s are 8–10.5 by 4.5–5.5 µm, ellipsoid, smooth, and yellowish in 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 spore-bearing cells, the basidia, are four-spored and measure 48–65 long by 6–8 µm thick. Pleurocystidia and cheilocystidia (specialized cystidia found on the gill faces and edges, respectively) are absent in this species. The pileipellis
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....
(cap cuticle) is made of a broad (175–350 µm) gelatinous zone, composed of loosely interwoven, slender (1.5–4 µm) hyphae; the surface 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 are a fuscous—a dark brownish-gray color. This hyphal arrangement is called an ixocutis, in which the hyphal walls swell up and gelatinize, giving a translucence to the layer that stands out in contrast to the underlying flesh. The layer of gelatizined hyphae is tenacious, and may be peeled off the cap as a film. Although 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 found on the hyphae that make up the flesh of the gill, none are found in the cap flesh nor in the pileipellis.
Edibility and antimicrobial activity
Hygrophorus agathosmus is edibleEdible 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...
, but considered bland. A study of the antioxidant
Antioxidant
An antioxidant is a molecule capable of inhibiting the oxidation of other molecules. Oxidation is a chemical reaction that transfers electrons or hydrogen from a substance to an oxidizing agent. Oxidation reactions can produce free radicals. In turn, these radicals can start chain reactions. When...
capacity of the mushroom was composed of at least five organic acid
Organic acid
An organic acid is an organic compound with acidic properties. The most common organic acids are the carboxylic acids, whose acidity is associated with their carboxyl group –COOH. Sulfonic acids, containing the group –SO2OH, are relatively stronger acids. The relative stability of the conjugate...
s: oxalic
Oxalic acid
Oxalic acid is an organic compound with the formula H2C2O4. This colourless solid is a dicarboxylic acid. In terms of acid strength, it is about 3,000 times stronger than acetic acid. Oxalic acid is a reducing agent and its conjugate base, known as oxalate , is a chelating agent for metal cations...
, citric
Citric acid
Citric acid is a weak organic acid. It is a natural preservative/conservative and is also used to add an acidic, or sour, taste to foods and soft drinks...
, malic
Malic acid
Malic acid is an organic compound with the formula HO2CCH2CHOHCO2H. It is a dicarboxylic acid which is made by all living organisms, contributes to the pleasantly sour taste of fruits, and is used as a food additive. Malic acid has two stereoisomeric forms , though only the L-isomer exists...
, quinic, and fumaric acid
Fumaric acid
Fumaric acid or trans-butenedioic acid is the chemical compound with the formula HO2CCH=CHCO2H. This white crystalline compound is one of two isomeric unsaturated dicarboxylic acids, the other being maleic acid. In fumaric acid the carboxylic acid groups are trans and in maleic acid they are cis...
s. Using a standard laboratory test to determine antimicrobial activity, Hygrophorus agathosmus was shown to inhibit the growth of various pathogen
Pathogen
A pathogen gignomai "I give birth to") or infectious agent — colloquially, a germ — is a microbe or microorganism such as a virus, bacterium, prion, or fungus that causes disease in its animal or plant host...
ic bacteria, including Escherichia coli
Escherichia coli
Escherichia coli is a Gram-negative, rod-shaped bacterium that is commonly found in the lower intestine of warm-blooded organisms . Most E. coli strains are harmless, but some serotypes can cause serious food poisoning in humans, and are occasionally responsible for product recalls...
, Enterobacter aerogenes
Enterobacter aerogenes
Enterobacter aerogenes is a Gram-negative, oxidase negative, catalase positive, citrate positive, indole negative, rod-shaped bacterium....
, Salmonella typhimurium, Pseudomonas aeruginosa
Pseudomonas aeruginosa
Pseudomonas aeruginosa is a common bacterium that can cause disease in animals, including humans. It is found in soil, water, skin flora, and most man-made environments throughout the world. It thrives not only in normal atmospheres, but also in hypoxic atmospheres, and has, thus, colonized many...
, 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...
, Staphylococcus epidermidis
Staphylococcus epidermidis
Staphylococcus epidermidis is one of thirty-three known species belonging to the genus Staphylococcus. It is part of human skin flora, and consequently part of human flora. It can also be found in the mucous membranes and in animals. Due to contamination, it is probably the most common species...
, and Bacillus subtilis
Bacillus subtilis
Bacillus subtilis, known also as the hay bacillus or grass bacillus, is a Gram-positive, catalase-positive bacterium commonly found in soil. A member of the genus Bacillus, B. subtilis is rod-shaped, and has the ability to form a tough, protective endospore, allowing the organism to tolerate...
; it also inhibits the growth of the yeast Candida albicans
Candida albicans
Candida albicans is a diploid fungus that grows both as yeast and filamentous cells and a causal agent of opportunistic oral and genital infections in humans. Systemic fungal infections including those by C...
and Saccharomyces cerevisiae
Saccharomyces cerevisiae
Saccharomyces cerevisiae is a species of yeast. It is perhaps the most useful yeast, having been instrumental to baking and brewing since ancient times. It is believed that it was originally isolated from the skin of grapes...
.
Similar species
Hygrophorus pustulatus resembles H. agathamosus and has a similar almond odor. However, the fruit bodies of H. pustulatus are smaller, and it produces larger spores (11–14 µm long). Hygrophorus occidentalis, which grows under conifers or oakOak
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...
, has a sticky stem and less pronounced almond odor. Hygrophorus marzuolus
Hygrophorus marzuolus
Hygrophorus marzuolus is a species of fungus in the Hygrophoraceae family. It was originally described by Elias Magnus Fries in 1821 as Agaricus marzuolus in 1821, and transferred to Hygrophorus in 1893 by Giacomo Bresadola....
is also similar in appearance, but it lacks a distinctive odor, and has smaller spores than H. agathamosus.
Habitat and distribution
Hygrophorus agathosmus is an ectomycorrhizal fungus, and it has been isolated, cultivated, and maintained as pure cultures of vegetative fungal inocula for artificial mycorrhizaMycorrhiza
A mycorrhiza is a symbiotic association between a fungus and the roots of a vascular plant....
tion of planting stock in forest nurseries. Fruiting bodies are found scattered 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...
and pine
Pine
Pines are trees in the genus Pinus ,in the family Pinaceae. They make up the monotypic subfamily Pinoideae. There are about 115 species of pine, although different authorities accept between 105 and 125 species.-Etymology:...
and in mixed woods
Temperate broadleaf and mixed forests
Mixed forests are a temperate and humid biome. The typical structure of these forests includes four layers. The uppermost layer is the canopy composed of tall mature trees ranging from 33 to 66 m high. Below the canopy is the three-layered, shade-tolerant understory that is roughly 9 to...
in the United States. The fungus is also found in Europe (Czech Republic, Poland, Russia, Turkey, and the United Kingdom), Africa, and India.