Mushroom

Amushroomortoadstoolis the fleshy,spore-bearingfruiting bodyof afungus, typically produced above ground, on soil, or on itsfoodsource.Toadstoolgenerally denotes one poisonous to humans.
The standard for the name "mushroom" is the cultivated white button mushroom,Agaricus bisporus; hence, the word "mushroom" is most often applied to those fungi (Basidiomycota,Agaricomycetes) that have a stem (stipe), a cap (pileus), and gills (lamellae, sing.lamella) on the underside of the cap. "Mushroom" also describes a variety of other gilled fungi, with or without stems; therefore the term is used to describe the fleshy fruiting bodies of someAscomycota. The gills produce microscopicsporeswhich help the fungus spread across the ground or its occupant surface.
Forms deviating from the standardmorphologyusually have more specific names, such as "bolete", "puffball", "stinkhorn", and "morel", and gilled mushrooms themselves are often called "agarics" in reference to their similarity toAgaricusor their orderAgaricales. By extension, the term "mushroom" can also refer to either the entire fungus when in culture, thethallus(calledmycelium) of species forming the fruiting bodies called mushrooms, or the species itself.
The terms "mushroom" and "toadstool" go back centuries and were never precisely defined, nor was there consensus on application. During the 15th and 16th centuries, the termsmushrom, mushrum, muscheron, mousheroms, mussheron, or musserounswere used.
The term "mushroom" and its variations may have been derived from the French wordmousseronin reference tomoss(mousse). Delineation between edible and poisonous fungi is not clear-cut, so a "mushroom" may be edible, poisonous, or unpalatable.The wordtoadstoolappeared first in14th centuryEngland as a reference for a "stool" fortoads, possibly implying an inedible poisonous fungus.
Identifying what is and is not a mushroom requires a basic understanding of theirmacroscopicstructure. Most arebasidiomycetesand gilled. Their spores, calledbasidiospores, are produced on the gills and fall in a fine rain of powder from under the caps as a result. At the microscopic level, the basidiospores are shot offbasidiaand then fall between the gills in the dead air space. As a result, for most mushrooms, if the cap is cut off and placed gill-side-down overnight, a powdery impression reflecting the shape of the gills (or pores, or spines, etc.) is formed (when the fruit body is sporulating). The color of the powdery print, called aspore print, is useful in both classifying and identifying mushrooms. Spore print colors include white (most common), brown, black, purple-brown, pink, yellow, and creamy, but almost never blue, green, or red.
While modern identification of mushrooms is quickly becoming molecular, the standard methods for identification are still used by most and have developed into a fine art harking back tomedievaltimes and theVictorian era, combined with microscopic examination. The presence of juices upon breaking, bruising-reactions, odors, tastes, shades of color, habitat, habit, and season are all considered by both amateur and professional mycologists. Tasting and smelling mushrooms carries its own hazards because of poisons andallergens.Chemical testsare also used for some genera.
In general, identification togenuscan often be accomplished in the field using a localfield guide. Identification tospecies, however, requires more effort. A mushroom develops from a button stage into a mature structure, and only the latter can provide certain characteristics needed for the identification of the species. However, over-mature specimens lose features and cease producing spores. Many novices have mistaken humid water marks on paper for white spore prints, or discolored paper from oozing liquids onlamellaedges for colored spored prints.
Typical mushrooms are the fruit bodies of members of the orderAgaricales, whosetype genusisAgaricusand type species is the field mushroom,Agaricus campestris. However in modernmolecularlydefinedclassifications, not all members of the order Agaricales produce mushroom fruit bodies, and many other gilled fungi, collectively called mushrooms, occur in other orders of the classAgaricomycetes. For example,chanterellesare in theCantharellales, false chanterelles such asGomphusare in theGomphales,milk-capmushrooms (Lactarius,Lactifluus) and russulas (Russula), as well asLentinellus, are in theRussulales, while the tough, leathery generaLentinusandPanusare among thePolyporales, butNeolentinusis in theGloeophyllales, and the little pin-mushroom genus,Rickenella, along with similar genera, are in theHymenochaetales.
Within the main body of mushrooms, in the Agaricales, are common fungi like the commonfairy-ring mushroom,shiitake,enoki,oyster mushrooms,fly agaricsand otherAmanitas,magic mushroomslike species ofPsilocybe,paddy straw mushrooms,shaggy manes, etc.
An atypical mushroom is thelobster mushroom, which is a fruitbody of aRussulaorLactariusmushroom that has been deformed by theparasiticfungusHypomyces lactifluorum. This gives the affected mushroom an unusual shape and red color that resembles that of a boiledlobster.
Other mushrooms are not gilled, so the term "mushroom" is loosely used, and giving a full account of their classifications is difficult. Some have pores underneath (and are usually calledboletes), others have spines, such as thehedgehog mushroomand othertooth fungi, and so on. "Mushroom" has been used forpolypores,puffballs,jelly fungi,coral fungi,bracket fungi,stinkhorns, andcup fungi. Thus, the term is more one of common application tomacroscopicfungal fruiting bodies than one having precisetaxonomicmeaning. Approximately 14,000 species of mushrooms are described.
A mushroom develops from a nodule, or pinhead, less than two millimeters in diameter, called aprimordium, which is typically found on or near the surface of thesubstrate. It is formed within themycelium, the mass of threadlikehyphaethat make up the fungus. The primordium enlarges into a roundish structure of interwoven hyphae roughly resembling an egg, called a "button". The button has a cottony roll of mycelium, theuniversal veil, that surrounds the developing fruit body. As the egg expands, the universal veil ruptures and may remain as a cup, orvolva, at the base of thestalk, or as warts or volval patches on the cap. Many mushrooms lack a universal veil, therefore they do not have either a volva or volval patches. Often, a second layer of tissue, thepartial veil, covers the bladelikegillsthat bearspores. As the cap expands the veil breaks, and remnants of the partial veil may remain as a ring, orannulus, around the middle of the stalk or as fragments hanging from the margin of the cap. The ring may be skirt-like as in some species ofAmanita, collar-like as in many species ofLepiota, or merely the faint remnants of a cortina (a partial veil composed of filaments resembling a spiderweb), which is typical of the genusCortinarius. Mushrooms lacking partial veils do not form an annulus.
The stalk (also called the stipe, or stem) may be central and support the cap in the middle, or it may be off-center or lateral, as in species ofPleurotusandPanus. In other mushrooms, a stalk may be absent, as in the polypores that form shelf-like brackets.Puffballslack a stalk, but may have a supporting base. Other mushrooms includingtruffles,jellies,earthstars, andbird's nestsusually do not have stalks, and a specialized mycological vocabulary exists to describe their parts.
The way the gills attach to the top of the stalk is an important feature of mushroom morphology. Mushrooms in the generaAgaricus,Amanita,LepiotaandPluteus, among others, have free gills that do not extend to the top of the stalk. Others havedecurrentgills that extend down the stalk, as in the generaOmphalotusandPleurotus. There are a great number of variations between the extremes of free and decurrent, collectively called attached gills. Finer distinctions are often made to distinguish the types of attached gills: adnate gills, which adjoin squarely to the stalk; notched gills, which are notched where they join the top of the stalk; adnexed gills, which curve upward to meet the stalk, and so on. These distinctions between attached gills are sometimes difficult to interpret, since gill attachment may change as the mushroom matures, or with different environmental conditions.
Ahymeniumis a layer of microscopic spore-bearing cells that covers the surface of gills. In the nongilled mushrooms, the hymenium lines the inner surfaces of the tubes ofboletesand polypores, or covers the teeth of spine fungi and the branches of corals. In the Ascomycota, spores develop within microscopic elongated, sac-like cells calledasci, which typically contain eight spores in each ascus. TheDiscomycetes, which contain the cup, sponge, brain, and some club-like fungi, develop an exposed layer of asci, as on the inner surfaces ofcup fungior within the pits ofmorels. ThePyrenomycetes, tiny dark-colored fungi that live on a wide range of substrates including soil, dung,leaf litter, and decaying wood, as well as other fungi, produce minute, flask-shaped structures calledperithecia, within which the asci develop.
In the basidiomycetes, usually four spores develop on the tips of thin projections calledsterigmata, which extend from club-shaped cells called abasidia. The fertile portion of theGasteromycetes, called agleba, may become powdery as in the puffballs or slimy as in thestinkhorns. Interspersed among the asci are threadlike sterile cells calledparaphyses. Similar structures calledcystidiaoften occur within the hymenium of the Basidiomycota. Many types of cystidia exist, and assessing their presence, shape, and size is often used to verify the identification of a mushroom.
The most important microscopic feature for identification of mushrooms is the spores. Their color, shape, size, attachment, ornamentation, and reaction tochemical testsoften can be the crux of an identification. A spore often has a protrusion at one end, called an apiculus, which is the point of attachment to the basidium, termed the apicalgerm pore, from which the hypha emerges when the spore germinates.
Many species of mushrooms seemingly appear overnight, growing or expanding rapidly. This phenomenon is the source of several common expressions in theEnglish languageincluding "to mushroom" or "mushrooming" (expanding rapidly in size or scope) and "to pop up like a mushroom" (to appear unexpectedly and quickly). In reality, all species of mushrooms take several days to form primordial mushroom fruit bodies, though they do expand rapidly by the absorption of fluids.
Thecultivated mushroom, as well as the commonfield mushroom, initially form a minutefruiting body, referred to as the pin stage because of their small size. Slightly expanded, they are called buttons, once again because of the relative size and shape. Once such stages are formed, the mushroom can rapidly pull in water from itsmyceliumand expand, mainly by inflating preformedcellsthat took several days to form in theprimordia.
Similarly, there are other mushrooms, likeParasola plicatilis(formerlyCoprinusplicatlis), that grow rapidly overnight and may disappear by late afternoon on a hot day after rainfall.The primordia form at ground level in lawns in humid spaces under thethatchand after heavy rainfall or indewyconditions balloon to full size in a few hours, release spores, and then collapse.
Not all mushrooms expand overnight; some grow very slowly and add tissue to their fruiting bodies by growing from the edges of the colony or by insertinghyphae. For example,Pleurotus nebrodensisgrows slowly, and because of this combined with human collection, it is nowcritically endangered.
Though mushroom fruiting bodies are short-lived, the underlying mycelium can itself be long-lived and massive. A colony ofArmillaria solidipes(formerly known asArmillaria ostoyae) inMalheur National Forestin theUnited Statesis estimated to be 2,400 years old, possibly older, and spans an estimated 2,200 acres (8.9 km).Most of the fungus is underground and in decaying wood or dying tree roots in the form of white mycelia combined with black shoelace-likerhizomorphsthat bridge colonized separated woody substrates.
Rawbrown mushroomsare 92% water, 4%carbohydrates, 2%proteinand less than 1%fat. In a 100 grams (3.5 ounces) amount, raw mushrooms provide 22caloriesand are a rich source (20% or more of theDaily Value, DV) ofB vitamins, such asriboflavin,niacinandpantothenic acid,selenium(37% DV) andcopper(25% DV), and a moderate source (10–19% DV) ofphosphorus,zincandpotassium(table). They have minimal or novitamin Candsodiumcontent.
Thevitamin Dcontent of a mushroom depends onpostharvesthandling, in particular the unintended exposure to sunlight. TheUS Department of Agricultureprovided evidence that UV-exposed mushrooms contain substantial amounts of vitamin D.When exposed toultraviolet(UV) light, even after harvesting,ergosterolin mushrooms is converted tovitamin D2,a process now used intentionally to supply fresh vitamin D mushrooms for thefunctional foodgrocerymarket.In a comprehensive safety assessment of producing vitamin D in fresh mushrooms, researchers showed that artificial UV light technologies were equally effective for vitamin D production as in mushrooms exposed to naturalsunlight, and that UV light has a long record of safe use for production of vitamin D in food.
Mushrooms are used extensively incooking, in manycuisines(notablyChinese,Korean,European, andJapanese). Humans have valued them as food since antiquity.
Most mushrooms sold insupermarketshave been commercially grown onmushroom farms. The most common of these,Agaricus bisporus, is considered safe for most people to eat because it is grown in controlled, sterilized environments. Several varieties ofA. bisporusare grown commercially, including whites, crimini, and portobello. Other cultivated species available at many grocers includeHericium erinaceus,shiitake,maitake(hen-of-the-woods),Pleurotus, andenoki. In recent years, increasing affluence in developing countries has led to a considerable growth in interest in mushroom cultivation, which is now seen as a potentially important economic activity for small farmers.
Chinais a major edible mushroom producer.The country produces about half of all cultivated mushrooms, and around 2.7 kilograms (6.0 lb) of mushrooms are consumed per person per year by 1.4 billion people.In 2014,Polandwas the world's largest mushroom exporter, reporting an estimated 194,000 tonnes (191,000 long tons; 214,000 short tons) annually.
Separating edible from poisonous species requires meticulous attention to detail; there is no single trait by which all toxic mushrooms can be identified, nor one by which all edible mushrooms can be identified. People who collect mushrooms for consumption are known as mycophagists,and the act of collecting them for such is known asmushroom hunting, or simply "mushrooming". Even edible mushrooms may produceallergicreactions in susceptible individuals, from a mildasthmaticresponse to severeanaphylacticshock.Even the cultivatedA. bisporuscontains small amounts ofhydrazines, the most abundant of which isagaritine(amycotoxinandcarcinogen).However, the hydrazines are destroyed by moderate heat when cooking.
A number of species of mushrooms arepoisonous; although some resemble certain edible species, consuming them could be fatal. Eating mushrooms gathered in the wild is risky and should only be undertaken by individuals knowledgeable in mushroom identification. Common best practice is for wild mushroom pickers to focus on collecting a small number of visually distinctive, edible mushroom species that cannot be easily confused with poisonous varieties. Common mushroom hunting advice is that if a mushroom cannot be positively identified, it should be considered poisonous and not eaten.
Many mushroom species producesecondary metabolitesthat can be toxic, mind-altering, antibiotic, antiviral, orbioluminescent. Although there are only a small number ofdeadly species, several others can cause particularly severe and unpleasant symptoms. Toxicity likely plays a role in protecting the function of the basidiocarp: the mycelium has expended considerable energy and protoplasmic material to develop a structure to efficiently distribute its spores. One defense against consumption and premature destruction is the evolution of chemicals that render the mushroom inedible, either causing the consumer to vomit the meal (seeemetics), or to learn to avoid consumption altogether. In addition, due to the propensity of mushrooms to absorbheavy metals, including those that are radioactive, as late as 2008, European mushrooms may have included toxicity from the 1986Chernobyl disasterand continued to be studied.
Mushrooms with psychoactive properties have long played a role in various native medicine traditions in cultures all around the world. They have been used as sacrament in rituals aimed at mental and physical healing, and to facilitate visionary states. One such ritual is theveladaceremony. A practitioner of traditional mushroom use is theshamanorcurandera(priest-healer).
Psilocybin mushrooms, also referred to as psychedelic mushrooms, possesspsychedelic properties. Commonly known as "magic mushrooms" or"'shrooms", they are openly available insmart shopsin many parts of the world, or on theblack marketin those countries which have outlawed their sale. Psilocybin mushrooms have been reported to facilitate profound and life-changing insights often described asmystical experiences. Recent scientific work has supported these claims, as well as the long-lasting effects of such induced spiritual experiences.
Psilocybin, a naturally occurring chemical in certainpsychedelic mushroomssuch asPsilocybe cubensis, is being studied for its ability to help people suffering from psychological disorders, such asobsessive–compulsive disorder. Minute amounts have been reported to stopclusterandmigraine headaches.A double-blind study, done byJohns Hopkins Hospital, showed psychedelic mushrooms could provide people an experience with substantial personal meaning and spiritual significance. In the study, one third of the subjects reported ingestion of psychedelic mushrooms was the single most spiritually significant event of their lives. Over two-thirds reported it among their five most meaningful and spiritually significant events. On the other hand, one-third of the subjects reported extremeanxiety. However the anxiety went away after a short period of time.Psilocybin mushrooms have also shown to be successful in treating addiction, specifically with alcohol and cigarettes.
A few species in the genusAmanita, most recognizablyA. muscaria, but alsoA. pantherina, among others, contain the psychoactive compoundmuscimol.The muscimol-containing chemotaxonomic group ofAmanitascontains noamatoxinsorphallotoxins, and as such are nothepatoxic, though if not properlycuredwill be non-lethallyneurotoxicdue to the presence ofibotenic acid. TheAmanitaintoxication is similar toZ-drugsin that it includesCNSdepressantandsedative-hypnoticeffects, but alsodissociationanddeliriumin high doses.
Some mushrooms are used infolk medicine.In a few countries,extracts, such aspolysaccharide-K,schizophyllan,polysaccharide peptide, orlentinan, are government-registeredadjuvant cancer therapies,but clinical evidence for efficacy and safety of these extracts in humans has not been confirmed.Although some mushroom species or their extracts may be consumed for therapeutic effects, some regulatory agencies, such as the USFood and Drug Administration, regard such use as adietary supplement, which does not have government approval or common clinical use as aprescription drug.
Mushrooms can be used fordyeingwooland other natural fibers. Thechromophoresofmushroom dyesare organic compounds and produce strong and vivid colors, and all colors of the spectrum can be achieved with mushroom dyes. Before the invention of syntheticdyes, mushrooms were the source of many textile dyes.
Some fungi, types ofpolyporesloosely called mushrooms, have been used as fire starters (known astinder fungi).
Mushrooms and other fungi play a role in the development of new biological remediation techniques (e.g., usingmycorrhizaeto spur plant growth) and filtration technologies (e.g. using fungi to lower bacterial levels in contaminated water).
There is an ongoing research in the field of genetic engineering aimed towards creation of the enhanced qualities of mushrooms for such domains as nutritional value enhancement, as well as medical use.