mushroom

—mushroomlike, adj. —mushroomy, adj.

/mush"roohm, -room/, n.

1. any of various fleshy fungi including the toadstools, puffballs, coral fungi, morels, etc.

2. any of several edible species, esp. of the family Agaricaceae, as Agaricus campestris (meadow mushroom or field mushroom), cultivated for food in the U.S.

3. anything of similar shape or correspondingly rapid growth.

4. a large, mushroom-shaped cloud of smoke or rubble, formed in the atmosphere as a result of an explosion, esp. a nuclear explosion.

adj.

5. of, consisting of, or containing mushrooms: a mushroom omelet.

6. resembling a mushroom in shape or form.

7. of rapid growth and often brief duration: mushroom towns of the gold-rush days.

v.i.

8. to spread, grow, or develop quickly.

9. to gather mushrooms.

10. to have or assume the shape of a mushroom.

[1350-1400; alter. (by folk etym.) of ME muscheron, musseroun < MF mousseron LL mussirion-, s. of mussirio]

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Fleshy spore-bearing structure of certain fungi (see fungus), typically of the class Basidiomycetes.

It arises from the mycelium, which may live hundreds of years or a few months, depending on its food supply. Some species grow cellular strands (hyphae) in all directions, forming a circular mat with a "fairy ring" of fruiting bodies around the outside. Popularly, "mushroom" refers to the edible sporophores, while "toadstool" refers to inedible or poisonous sporophores, but there is no scientific distinction between the two names. Mushrooms are classified by cap shape. Umbrella-shaped sporophores with spore-shedding gills on the undersurface are found chiefly in the agaric family (Agaricaceae). Mushrooms that bear spores in an easily detachable layer on the underside of the cap belong to the family Boletaceae. Together the agarics and boletes include most of the forms known as mushrooms. The highly prized edible chanterelle is a bolete. The morels (class Ascomycetes) are popularly included with the true mushrooms because of their shape and fleshy structure. Since some poisonous mushrooms closely resemble edible ones, mushrooms intended for eating must be accurately identified. Mushroom poisoning can cause nausea, diarrhea, vomiting, cramps, hallucinations, coma, and sometimes death.

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▪ fungus

   the conspicuous umbrella-shaped fruiting body (sporophore) of certain fungi, typically of the order Agaricales (q.v.) in the phylum Basidiomycota (q.v.) but also of some other groups. Popularly, the term mushroom is used to identify the edible sporophores; the term toadstool is often reserved for inedible or poisonous sporophores. There is, however, no scientific distinction between the two names, and either can be properly applied to any fleshy fungus fruiting structure. In a very restricted sense, mushroom indicates the common edible fungus of fields and meadows (Agaricus campestris). A very closely related species, A. bisporus, is the mushroom grown commercially and seen in markets.

      Umbrella-shaped sporophores are found chiefly in the agaric family (Agaricaceae), members of which bear thin, bladelike gills on the undersurface of the cap from which the spores are shed. The sporophore of an agaric consists of a cap (pileus) and stalk (stipe). The sporophore emerges from an extensive underground network of threadlike strands ( mycelium). An example of an agaric is the honey mushroom (Armillaria mellea). Mushroom mycelia may live hundreds of years or die in a few months, depending on the available food supply. As long as nourishment is available and temperature and moisture are suitable, a mycelium will produce a new crop of sporophores each year during its fruiting season.

      Fruiting bodies of some mushrooms occur in arcs or rings called fairy rings (fairy ring). The mycelium starts from a spore falling in a favourable spot and producing strands (hyphae) that grow out in all directions, eventually forming a circular mat of underground hyphal threads. Fruiting bodies, produced near the edge of this mat, may widen the ring for hundreds of years.

      A few mushrooms belong to the order Boletales (Boletaceae) (q.v.), which bear pores in an easily detachable layer on the underside of the cap. The agarics and boletes include most of the forms known as mushrooms. Other groups of fungi, however, are considered to be mushrooms, at least by laymen. Among these are the hydnums or hedgehog mushrooms, which have teeth, spines, or warts on the undersurface of the cap (e.g., Dentinum repandum, Hydnum imbricatum) or at the ends of branches (e.g., Hydnum coralloides, Hericium caput-ursi). The polypores, shelf fungi, or bracket fungi (order Polyporales; q.v.) have tubes under the cap as in the boletes, but they are not in an easily separable layer. Polypores usually grow on living or dead trees, sometimes as destructive pests. Many of them renew growth each year and thus produce annual growth layers by which their age can be estimated. Examples include the dryad's saddle (Polyporus squamosus), the beefsteak fungus (Fistulina hepatica), the sulfur fungus (Polyporus sulphureus), the artist's fungus (Ganoderma applanatum), and species of the genera Fomes and Trametes. The clavarias, or club fungi (e.g., Clavaria, Ramaria), are shrublike, clublike, or coral-like in growth habit. One club fungus, the cauliflower fungus (Sparassis crispa), has flattened clustered branches that lie close together, giving the appearance of the vegetable cauliflower. The cantharelloid fungi (Cantharellus and its relatives) are club-, cone-, or trumpet-shaped mushroom-like forms with an expanded top bearing coarsely folded ridges along the underside and descending along the stalk. Examples include the highly prized edible chanterelle (C. cibarius) and the horn-of-plenty mushroom (Craterellus cornucopioides). Puffballs (family Lycoperdaceae; q.v.), stinkhorns (q.v.), earthstars (a kind of puffball), and bird's nest fungi are usually treated with the mushrooms. The morels (Morchella, Verpa) and false morels or lorchels (Gyromitra, Helvella) of the phylum Ascomycota (q.v.) are popularly included with the true mushrooms because of their shape and fleshy structure; they resemble a deeply folded or pitted conelike sponge at the top of a hollow stem. Some are among the most highly prized edible fungi (e.g., Morchella esculenta). Another group of ascomycetes includes the cup fungi (see cup fungus), with a cuplike or dishlike fruiting structure, sometimes highly coloured.

      Other unusual forms, not closely related to the true mushrooms, but often included with them, are the jelly fungi (Tremella species), the ear fungus or Jew's ear (Auricularia auriculara-judae), and the edible truffle (q.v.).

      Mushrooms are free of cholesterol and contain small amounts of essential amino acids and B vitamins. However, their chief worth is as a specialty food of delicate, subtle flavour and agreeable texture. By fresh weight, the common commercially grown mushroom is more than 90 percent water, less than 3 percent protein, less than 5 percent carbohydrate, less than 1 percent fat, and about 1 percent mineral salts and vitamins.

      Poisoning by wild mushrooms is common and may be fatal or produce merely mild gastrointestinal disturbance or slight allergic reaction. It is important that every mushroom intended for eating be accurately identified (see mushroom poisoning).

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