Mushroom

For other uses, see Mushroom (disambiguation).

"Mushrooms" redirects here. For the 1991 television episode, see Mushrooms (Law & Order).

The mushroom Amanita muscaria, commonly known as "fly agaric"

A mushroom is the fleshy, spore-bearing fruiting body of a fungus, typically produced above ground on soil or on its food source. 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, just as do store-bought white mushrooms.

The word "mushroom" can also be used for a wide variety of gilled fungi, with or without stems, and the term is used even more generally, to describe both the fleshy fruiting bodies of some Ascomycota and the woody or leathery fruiting bodies of some Basidiomycota, depending upon the context of the word.

Forms deviating from the standard morphology usually have more specific names, such as "puffball", "stinkhorn", and "morel", and gilled mushrooms themselves are often called "agarics" in reference to their similarity to Agaricus or their placement in the order Agaricales. By extension, the term "mushroom" can also designate the entire fungus when in culture or the thallus (called a mycelium) of species forming the fruiting bodies called mushrooms, or the species itself.

Identification

Morphological characteristics of the caps of mushrooms.

Identifying mushrooms requires a basic understanding of their macroscopic structure. Most are Basidiomycetes and gilled. Their spores, called basidiospores, 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 off basidia and 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 a spore print, is used to help classify mushrooms and can help to identify them. Spore print colors include white (most common), brown, black, purple-brown, pink, yellow, and cream, 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 to medieval times and the Victorian 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 and allergens. Chemical tests are also used for some genera.

In general, identification to genus can often be accomplished in the field using a local mushroom guide. Identification to species, however, requires more effort; one must remember that 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 on lamella edges for colored spored prints.

Classification

The genus Trichaptum, an example of a polypore, a mushroom without a stalk, fruiting on a log

Trametes versicolor another type of polypore mushroom.

Main articles: Sporocarp (fungi), Basidiocarp, and Ascocarp

Typical mushrooms are the fruitbodies of members of the order Agaricales, whose type genus is Agaricus and type species is the field mushroom, Agaricus campestris. However, in modern molecularly defined classifications, not all members of the order Agaricales produce mushroom fruitbodies, and many other gilled fungi, collectively called mushrooms, occur in other orders in the class Agaricomycetes. For example, chanterelles are in the Cantharellales, false chanterelles like Gomphus are in the Gomphales, milk mushrooms (Lactarius) and russulas (Russula) as well as Lentinellus are in the Russulales, while the tough leathery genera Lentinus and Panus are among the Polyporales, but Neolentinus is in the Gloeophyllales, and the little pin-mushroom genus, Rickenella, along with similar genera, are in the Hymenochaetales.

Within the main body of mushrooms, in the Agaricales, are common fungi like the common fairy-ring mushroom (Marasmius oreades), shiitake, enoki, oyster mushrooms, fly agarics, and other amanitas, magic mushrooms like species of Psilocybe, paddy straw mushrooms, shaggy manes, etc.

An atypical mushroom is the Lobster mushroom, which is a deformed, cooked-lobster-colored parasitized fruitbody of a Russula or Lactarius colored and deformed by the mycoparasitic Ascomycete Hypomyces lactifluorum.

Other mushrooms are non-gilled, and then the term "mushroom" is loosely used, so that it is difficult to give a full account of their classifications. Some have pores underneath (and are usually called boletes), others have spines, such as the hedgehog mushroom and other tooth fungi, and so on. "Mushroom" has been used for polypores, puffballs, jelly fungi, coral fungi, bracket fungi, stinkhorns, and cup fungi. Thus, the term mushroom is more one of common application to macroscopic fungal fruiting bodies than one having precise taxonomic meaning. There are approximately 14,000 described species of mushrooms.

Mushroom vs. toadstool

The relative sizes of the cap (pileus) and stalk (stipe) vary widely. Shown here is a species of Macrolepiota.

The terms "Mushroom" and "Toadstool" go back centuries and were never precisely defined, nor was there consensus on application.

The term "toadstool" was often, but not exclusively, applied to poisonous mushrooms or to those that have the classic umbrella-like cap-and-stem form. Between 1400 and 1600 A.D., the terms tadstoles, frogstooles, frogge stoles, tadstooles, tode stoles, toodys hatte, paddockstool, puddockstool, paddocstol, toadstoole, and paddockstooles sometimes were used synonymously with mushrom, mushrum, muscheron, mousheroms, mussheron, or musserouns.

The word has apparent analogies in Dutch padde(n)stoel (toad-stool/chair, mushroom) and German Krötenschwamm (toad-fungus, alt. word for panther cap). Others have proposed a connection with German "Todesstuhl" (lit. "death's chair"). Since Tod is a direct cognate to death, in that case it would be a German borrowing.

The term "mushroom" and its variations may have been derived from the French word mousseron in reference to moss (mousse). The toadstool's connection to toads may be direct, in reference to some species of poisonous toad, or may just be a case of phono-semantic matching from the German word. However, there is no clear-cut delineation between edible and poisonous fungi, so that a "mushroom" may be edible, poisonous, or unpalatable. The term "toadstool" is nowadays used in storytelling when referring to poisonous or suspect mushrooms. The classic example of a toadstool is Amanita muscaria.

Growth rates

Mushroom popping up through macadam in summer near Paris

Many species of mushrooms seemingly appear overnight, growing or expanding rapidly. This phenomenon is the source of several common expressions in the English language including "to mushroom" or "mushrooming" (expanding rapidly in size or scope) and "to pop up like a mushroom" (to appear unexpectedly and quickly). In actuality all species of mushrooms take several days to form primordial mushroom fruit bodies, though they do expand rapidly by the absorption of fluids.

The cultivated mushroom as well as the common field mushroom initially form a minute fruiting 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 its mycelium and expand, mainly by inflating preformed cells that took several days to form in the primordia.

Similarly, there are even more ephemeral mushrooms, like Parasola plicatilis (formerly Coprinus plicatlis), that literally appear 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 the thatch and after heavy rainfall or in dewy conditions balloon to full size in a few hours, release spores, and then collapse. They "mushroom" to full size.

Not all mushrooms expand overnight; some grow very slowly and add tissue to their fruitbodies by growing from the edges of the colony or by inserting hyphae. For example Pleurotus nebrodensis grows slowly, and because of this combined with human cultivation, it is now critically endangered.

Size and age

Yellow, flower pot mushrooms (Leucocoprinus birnbaumii) at various states of development

Though mushroom fruiting bodies are short-lived, the underlying mycelium can itself be long-lived and massive. A colony of Armillaria ostoyae in Malheur National Forest in the United States is estimated to be 2,400 years old, possibly older, and spans an estimated 2,200 acres. Most of the fungus is underground and in decaying wood or dying tree roots in the form of white mycelia combined with black shoelace-like rhizomorphs that bridge colonized separated woody substrates.

Human use

The Agaricus bisporus, one of the most widely cultivated mushrooms in the world.

Further information: Ethnomycology

Edible mushrooms

Main articles: Edible mushroom, Mushroom hunting, and Fungiculture

Edible mushrooms are used extensively in cooking, in many cuisines (notably Chinese, European, and Japanese). Though mushrooms are commonly thought to have little nutritional value, many species are high in fiber and provide vitamins such as thiamine, riboflavin, niacin, biotin, cobalamins, ascorbic acid. Though not normally a significant source of vitamin D, some mushrooms can become significant sources after exposure to ultraviolet light, though this also darkens their skin. Mushrooms are also a source of some minerals, including selenium, potassium and phosphorus.

Mushrooms for sale at Borough Market

Most mushrooms that are sold in supermarkets have been commercially grown on mushroom farms. The most popular of these, Agaricus bisporus, is generally considered safe for most people to eat because it is grown in controlled, sterilized environments, though some individuals do not tolerate it well. Several varieties of A. bisporus are grown commercially, including whites, crimini, and portobello. Other cultivated species now available at many grocers include shiitake, maitake or hen-of-the-woods, oyster, and enoki. 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.

Mushroom and Truffle output in 2005

There are a number of species of mushroom that are poisonous, and although some resemble certain edible species, eating them could be fatal. Eating mushrooms gathered in the wild is risky and should not be undertaken by individuals not knowledgeable in mushroom identification, unless the individuals limit themselves to a relatively small number of good edible species that are visually distinctive. A. bisporus contains carcinogens called hydrazines, the most abundant of which is agaritine. However, the carcinogens are destroyed by moderate heat when cooking.

More generally, and particularly with gilled mushrooms, 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.

Additionally, even edible mushrooms may produce an allergic reaction, from a mild asthmatic response to severe anaphylaxis shock.

People who collect mushrooms for consumption are known as mycophagists, and the act of collecting them for such is known as mushroom hunting, or simply "Mushrooming".

China is the world's largest edible mushroom producer.

Toxic mushrooms

Main article: Mushroom poisoning

Young "Amanita phalloides" mushrooms next to some matches.

Of central interest with respect to the chemical properties of mushrooms is the fact that many species produce secondary metabolites that render them toxic, mind-altering, or even bioluminescent.

Although there are only a small number of deadly 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 (see emetics) the meal, or to learn to avoid consumption altogether.

Psychoactive mushrooms

Main article: Psilocybin mushrooms

Hallucinogenic Psilocybe mushrooms

Mushrooms that have psychoactive properties have long played a role in some native medicine traditions, where they have been used for mental and physical healing, and to facilitate visionary states. One such ritual is the velada ceremony. A practitioner of traditional mushroom use is the shaman and curandera (priest-healer).

Psilocybian mushrooms possess psychedelic properties. Commonly known as "magic mushrooms," "mushies" or "shrooms," they are openly available in smart shops in many parts of the world, or on the black market in those countries that have outlawed their sale. Psilocybian mushrooms have been reported as facilitating profound and life-changing insights often described as mystical 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 certain psychedelic mushrooms like Psilocybe cubensis, is being studied for its ability to help people suffering from psychological disorders, such as obsessive-compulsive disorder. Minute amounts have been reported to stop cluster and migraine headaches. A double-blind study, done by the John Hopkins Hospital, showed that psychedelic mushrooms could provide people an experience with substantial personal meaning and spiritual significance. In the study, one third of the subjects reported that 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 extreme anxiety.

The finding of spores in the upper atmosphere has led some mycologists to suspect that fungus may be an inter planetary species. Thus the "trip" provided by Psilocybin may be a form of extraterrestrial communication.

Amanita muscaria pictured above is also psychoactive. The active constituents are Ibotenic acid and Muscimol. The Muscaria chemotaxonomic group of Amanitas contain no amatoxins or phallotoxins, and are not hepatoxic. Some dry these in the sun to transform the Ibotenic acid into the more psychoactive Muscimol.

Medicinal mushrooms

Main article: Medicinal mushrooms

The most well known "medicinal mushroom", Reishi.

Many species of medicinal mushrooms have been used in folk medicine for thousands of years. The use of medicinal mushrooms in folk medicine, is best documented in the East. Medicinal mushrooms are now the subject of study for many ethnobotanists and medical researchers. The ability of some mushrooms to inhibit tumor growth and enhance aspects of the immune system has been a subject of research for approximately 50 years. International mushroom research continues today, with a focus on mushroom's that may have hypoglycemic activity, anti-cancer activity, anti-pathogenic activity, and immune system enhancing activity. Recent research has found that the oyster mushroom naturally contains the cholesterol drug lovastatin, mushrooms produce large amounts of vitamin D when exposed to UV light, and that certain fungi may be a future source of taxol. To date, penicillin, lovastatin, ciclosporin, griseofulvin, cephalosporin, ergometrine, and statins are the most famous pharmaceuticals which have been isolated from the fungi kingdom.

Other uses

"Tinder fungi"

Mushrooms can be used for dyeing wool and other natural fibers. The chromophores of mushrooms are organic compounds and produce strong and vivid colors, and all colors of the spectrum can be achieved with mushroom dyes. Before the invention of synthetic dyes mushrooms were the source of many textile dyes.

Some fungi, types of polypores loosely called mushrooms, have been used as fire starters (known as tinder fungi).

Mushrooms and other fungi play a role in the development of effective biological remediation and filtration technologies. The US Patent and Trademark Office can be searched for patents related to the latest developments in mycoremediation and mycofiltration.

Further reading

• Lindequist, U. (2005). "The pharmacological potential of mushrooms". Evid Based Complement Alternat Med. 2: 285. doi:10.1093/ecam/neh107. PMID 16136207. {{cite journal}}: Cite has empty unknown parameter: |unused_data= (help); Text "Sep;2(3):285-99." ignored (help)

References

• Edible Wild Mushrooms of North America: A Field-to-kitchen Guide (1992) ISBN 0-292-72080-0
• Mushrooms of Northeastern North America (1997) ISBN 0-8156-0388-6
• All That the Rain Promises, and More (1991) ISBN 0-89815-388-3
• Growing Gourmet and Medicinal Mushrooms (2000) ISBN 1-58008-175-4
• Mushroom Cultivator: A Practical Guide to Growing Mushrooms at Home (1983) ISBN 0-9610798-0-0
• Mushrooms: Cultivation, Nutritional Value, Medicinal Effect, and Environmental Impact (2004) ISBN 0-8493-1043-1
• Mycelium Running: How Mushrooms Can Help Save The World (2005) ISBN 1-58008-579-2
• Mushrooms Demystified: A Comprehensive Guide to the Fleshy Fungi (1986) ISBN 0-89815-169-4
• Psilocybin Mushroom Handbook: Easy Indoor and Outdoor Cultivation (2004) ISBN 0-932551-64-5
• Psilocybin Mushrooms of the World (1996) ISBN 0-89815-839-7

External links

Identification

• Mushroom Expert
• MykoWeb
• An Aid to Mushroom Identification, Simon's Rock College
• Online Edible Wild Mushroom Field Guide
• Mushroom Observer (All images are made available under a Creative Commons license.)

Research associations

• Mushroom Mania; the Newsletter
• North American Mycological Association
• International Society for Mushroom Science
• Pacific Northwest Fungi Online Journal