From Academic Kids
A mushroom is an above-ground fruiting body (that is, a spore-producing structure) of a fungus, having a shaft and a cap; and by extension, the entire fungus producing the fruiting body of such appearance, the former consisting of a network (called the mycelium) of filaments or hyphae. In a much broader sense, mushroom is applied to any visible fungus, or especially the fruiting body of any fungus, with the mycelium usually being hidden under bark, ground, rotted wood, leaves, etc. The technical term for the spore-producing structure of "true" mushrooms is the basidiocarp. The term "toadstool" is used typically to designate a basidiocarp that is poisonous to eat.
Types of mushrooms
The main types of mushrooms are agarics, boletes, chanterelles, tooth fungi, polypores, puffballs, jelly fungi, coral fungi, bracket fungi, stinkhorns, and cup fungi. Mushrooms and other fungi are studied by mycologists. The "true" mushrooms are classified as Basidiomycota (also known as "club fungi"). A few mushrooms are classified by mycologists as Ascomycota (the "cup fungi"), the morel and truffle being good examples. Thus, the term mushroom is more one of common application to macroscopic fungal fruiting bodies than one having precise taxonomic meaning.
Mushrooms are used extensively in cooking many cuisines. Though commonly thought to contain little nutritional value, many varieties of mushrooms are high in fiber and protein, and provide vitamins such as thiamine, riboflavin, niacin, biotin, and ascorbic acid, and minerals including iron, selenium, potassium and phosphorus. However, a number of species of mushrooms are poisonous, and these may resemble edible varieties, although eating them could be fatal. Picking mushrooms in the wild is risky — riskier than gathering edible plants — and a practice not to be undertaken by amateurs. The problem is due to the fact that separating edible from poisonous species is dependent upon the application of only a few easily recognizable traits. People who collect mushrooms for consumption are known as mushroom hunters, and the act of collecting them as such is called mushroom hunting — an activity with a potentially deadly outcome that one should not attempt without knowing how to recognize the poisonous species.
Identifying mushrooms requires a basic understanding of their macroscopic structure. A "typical" mushroom consists of a cap or pileus supported on a stem or stipe. Both can have a variety of shapes and be ornamented in various ways. The underside of the cap (in agarics) is fitted with gills or lamellae where the actual spores are produced. How the gills are attached is another important characteristic used in identification. In the boletes, the gills are replaced by small openings called pores. Bracket fungi essentially lack a stipe, and the cap is attached like a bracket to the substratum, usually a log or tree trunk. Some bracket fungi have gills, others have pores.
In general, identification to genus can be accomplished in the field using a local mushroom guide. Identification to species requires more work. Realize that a mushroom develops from a young bud into a mature structure and only the latter can provide certain identification of the species. Examination of mature spores, or at least knowing their color, is often essential. And to this end, a common method used to assist in identification is the spore print.
Of central interest with respect to chemical properties of mushrooms is the fact that many species produce secondary metabolites that render them toxic, mind-altering, or even bioluminescent.
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 regurgitate (see emetics) the meal or avoid consumption altogether (see Mushroom poisoning).
Psilocybian 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 (see Psychedelic mushroom). 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. It was reportedly used by the Vikings to induce a fearless and aggressive mind state preparatory to going into battle.
Currently, many species of mushrooms and fungi utilized as folk medicines for thousands of years are under intense study by ethnobotanists and medical researchers. Maitake, shiitake, and reishi are prominent among those being researched for their potential anti-cancer, anti-viral, and/or immunity-enhancement 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, and has been used in the west to potentiate religious experience. See Good Friday experiment
Because of their psychoactive properties, some mushrooms have played a role in native medicine, where they have been used 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, curandera (priest-healer), Maria Sabina.