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Mushroom

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 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. However, "mushroom" can also refer to 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 form 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, "mushroom" can also designate the entire fungus when in culture or the thallus (called a mycelium) of species forming the fruiting bodies called mushrooms.

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Identification

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 of 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 fruitbody 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 mycologists, amateur and professional alike. Tasting and smelling mushrooms carries its own hazards because of poisons and allergens. Chemical spot 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

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.^[1]

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.^[2]

Mushroom vs. toadstool

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.^[3] The term "mushroom" and its variations may have been derived from the French word mousseron in reference to moss (mousse). There may have been a direct connection to toads (in reference to poisonous properties) for toadstools. 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

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 fruitbodies, 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 ([1] 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. The slang term "mushrooms" is a gang-related term for victims accidentally shot as collateral damage simply because they popped up suddenly, as do fungal mushrooms.^[4]

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.

Size and age

Though mushrooms are thought to be short-lived, the fungus that forms the mushroom fruitbodies 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.^[5]

Human use

Further information: Ethnomycology

Edible mushrooms

Main articles: Edible mushrooms, 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 (B₁), riboflavin (B₂), niacin (B₃), biotin (B₇), cobalamins (B₁₂), and ascorbic acid (C), as well as minerals, including iron, selenium, potassium, and phosphorus. Mushrooms have been gaining a higher profile for containing the antioxidants ergothioneine and selenium. Most mushrooms that are sold in supermarkets have been commercially grown on mushroom farms. The most popular of these, Agaricus bisporus, is 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 portabello. Other cultivated species now available at many grocers include shiitake, maitake or hen-of-the-woods, oyster, and enoki.

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. 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.

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".

Toxic mushrooms

Main article: Mushroom poisoning

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. Though there are only a small number of deadly species, several have 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 avoid consumption altogether.

Psychoactive mushrooms

Main article: Psychedelic mushrooms

Psilocybin mushrooms possess psychedelic properties. They are commonly known as "magic mushrooms" or "shrooms" and are available in smart shops in many parts of the world, though some countries have outlawed their sale. A number of other mushrooms are eaten for their psychoactive effects, such as fly agaric, which is used for shamanic purposes by tribes in northeast Siberia, Russia. They have also been used in the West to potentiate, or increase, religious experiences. Because of their psychoactive properties, some mushrooms have played a role in native medicine, where they have been used in an attempt to effect mental and physical healing, and to facilitate visionary states. One such ritual is the Velada ceremony. A representative figure of traditional mushroom use is the shaman and curandera (priest-healer) María Sabina.

Medicinal mushrooms

Currently, many species of mushrooms and fungi used in folk medicine for thousands of years are under intense study by ethnobotanists and medical researchers. Maitake, shiitake, chaga, and reishi are prominent among those being researched for their potential anti-cancer, anti-viral, or immunity-enhancing properties. Psilocybin, originally an extract of certain psychedelic mushrooms, is being studied for its ability to help people suffering from mental disease, such as obsessive-compulsive disorder. Minute amounts have been reported to stop cluster and migraine headaches.[2]

Other uses

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 primary source of textile dyes. This technique has survived in Finland, and many Middle Ages re-enactors have revived the skill.^{[citation needed]} Some fungi, types of polypores loosely called mushrooms, have been used as fire starters (known as tinder fungi). Ötzi the Iceman was found carrying such fungi. Mushrooms and other fungi will likely play an increasingly important 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.

References

^ botit.botany.wisc.edu - The lobster mushroom
^ Chang, S., and Miles, P.G., Mushrooms, Cultivation, Nutritional Value, Medicinal Effect, and Environmental Impact, CRC Press, 2004
^ Ramsbottom J (1954). Mushrooms & Toadstools. A study of the Activities of Fungi.
^ Sherman LW et al (1989). "Stray bullets and “mushrooms”: Random shootings of bystanders in four cities, 1977–1988". J. Quantitative Criminology 5(4): 297-316.
^ A Fungus Among Us. Extreme Science (n.d.). Retrieved on 2007-11-14.