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Mushrooms Toadstool Fungi Poisonous Mushrooms

Mushrooms Toadstool Fungi Poisonous Mushrooms

Mushrooms/Toadstool,Fungi, Poisonous Mushrooms,
technically confined to members of a family of fungi with gills, but in popular usage any of the larger fleshy or woody fungi. The application of the term mushroom to edible species only and the term toadstool to those considered poisonous or otherwise objectionable has no scientific basis. For example, two poisonous fungi may be less closely related than are a poisonous species and an edible one.

Of the thousands of species of mushrooms known throughout the world, the great majority are tough, woody, bitter, tasteless, or of such rare occurrence that they are of no interest as food. A few species produce death or serious illness when eaten. No simple rule exists for distinguishing edible and poisonous mushrooms, but the characteristics of the more common edible species can be readily learned, and collecting activities should be confined to such species. Morels, puffballs, and other species described below are not ordinarily confused with dangerous types; whenever doubt arises, the only safe procedure is to discard all suspicious mushrooms. Fresh commercially grown mushrooms can always be eaten with safety.

II  EDIBLE MUSHROOMS, 

The mushroom species usually grown commercially attains a size of 5 to 10 cm (2 to 4 in) tall and has a fleshy cap from about 2 to 10 cm (1‚ to 4 in) across. When the mushroom is ripe, the cap is white or slightly brownish above and pink on the underside. With age, the entire fruiting body changes to dark brown. In the young mushroom the margin of the cap is jointed to the stem by a membranous collar, which breaks at maturity to expose the gills on the undersurface of the cap.

Mushrooms are cultivated commercially in caves, dark cellars, or specially constructed mushroom houses in which the proper humidity and temperature are maintained. They are grown in beds consisting of a mixture of rotted manure and chemically treated straw, over which a layer of soil (casing soil) is spread. The vegetative portion of the fungus, known as the mycelium, or spawn, is used for planting, or spawning, the beds. The mycelium is grown in pure culture under laboratory conditions, thus ensuring freedom from insect and fungus contaminants. In a few weeks the spawn invests the entire bed, and the mushroom fruiting bodies, or sporophores, begin to appear. Several flushes, or crops, of mushrooms develop in this manner from each spawning. The mushrooms are harvested at frequent intervals and transported promptly to market.


The field or garden mushroom is a common and widespread species in pastures, grassy areas, and manured fields during the summer season. It has the same desirable qualities as the cultivated species, and until recently both were considered forms of the same species.

The chanterelle, a gill fungus with a nutlike flavor, has been popular in Europe since ancient Roman times. Chanterelles are abundant in coniferous and hardwood forests in midsummer. This mushroom grows from 5 to 10 cm (2 to 4 in) tall and has an irregularly lobed orange or yellow cap that is funnel-shaped when young, but that expands and becomes depressed at the center as it ages. The crisp, heavy specimens are the most desirable for eating.

The edible pore mushrooms grow in open deciduous woods during summer and early autumn. The king boletus has a stem 5 to 15 cm (2 to 6 in) tall and a fleshy, brown cap 10 to 15 cm (4 to 6 in) across. The cap is covered with a network of fine veins that are white when young and change in stages from yellow to a greenish hue as the mushroom ages. This mushroom is most tender when the veins are pale yellow. Many other species of the same genus are suitable for food.

The oyster mushroom has a pleasant, oysterlike flavor and is often prepared by dipping in egg and frying slowly. This mushroom grows in bracketlike clusters on decaying tree trunks. It is almost stemless. The fleshy, tender cap is 8 to 13 cm (3 to 5 in) across, tawny olive-colored when young, but fades with age. The oyster mushroom is abundant from June to November.


The sulfur mushroom develops on rotten logs, stumps, and even on standing trees, producing a brown wood rot. The fruiting bodies, appearing from late summer through fall, develop as bright-orange and yellow rosettes or as a series of fan-shaped shelves. These mushrooms may reach a breadth of several meters and a weight of several kilograms. Spores are produced in enormous numbers in minute pores on the lower surface. The fungus is edible if gathered in the young, growing stage, but rapidly becomes dry, tough, and honeycombed by insect larvae.

The shaggy-mane is a common and widespread mushroom species appearing from spring until fall in lawns, gardens, and other open spaces. This species grows singly or in clumps and may occur in the same area year after year. It is easily recognized by the attractive cylindrical caps, which are rounded above, up to 5 cm (2 in) wide and 15 cm (6 in) long, and covered with soft, shaggy brown scales. The caps do not expand with maturity, as in most other mushrooms, and the tightly packed gills soon dissolve into a black, inky fluid. The shaggy-mane is considered one of the choicest edible species. Blackened portions should be discarded before the mushroom is eaten. Some related species cause poisoning when alcohol is taken within five days after ingestion of the mushroom.

The giant puffballs do not resemble ordinary mushrooms in shape. They are very large and globose, are 8 to 51 cm (3 to 20 in) in diameter, and have no gills or pores; the spores are borne internally. The fruiting body is creamy white in the edible stage but later becomes brown and powdery and unsuitable for food. Puffballs grow in grassy places and at the edge of woods during late summer and early fall. They do not resemble poisonous or otherwise offensive fungi. Other puffballs are edible as long as the tissues within are not discolored or larva-infested. Species that are brown to purple within should be avoided.

The true morels and related species are excellent edible forms. They grow about 5 to 10 cm (2 to 4.5 in) tall and have a cap about 2 to 3 cm (1 to 1.5 in) wide. The cap is greenish-yellow to dark olive in color and is ribbed and pitted like a honeycomb. Morels are commonly found in the spring in old apple orchards and woods, especially under butternut trees, and on burned-over land or areas where wood ashes have been scattered. The morels should not be confused with the false morels, the edibility of which is definitely suspect.

Truffles, especially the Périgord truffle, are subterranean European fungi and probably the most highly prized of the edible fungi. The flesh of all truffles is nearly white when young; as the truffle matures, the flesh becomes darker with a marbling of lighter tissue. Because truffles have a distinctive odor, their underground location may be determined by animals trained for this purpose. Pigs and dogs are the usual truffle hunters. Truffles and the livers of fattened geese are the chief constituents of pâté de foie gras.

III  POISONOUS MUSHROOMS ,

The number of poisonous fungus species is probably more than 200. Many mushrooms formerly considered doubtful or poisonous have been found to be edible. The original misconception in these cases probably resulted from observation of sickness following the consumption of mushrooms that were no longer fresh and that contained poisons that were similar to those generated in putrefied meats and vegetables.

Some mushrooms, however, especially amanitas, are extremely poisonous and are often fatal if ingested by humans. They contain organic toxins that destroy cells in the central nervous system, blood vessels, kidneys, liver, and musculature. Medically, the most important toxins formed by fungi are ibotenic acid, muscarine, monomethylhydrazine, and the amatoxins. Ibotenic acid is the principal toxin in the fly amanita, even though muscarine is so named because it is found in that mushroom; muscarine is also synthesized by other poisonous mushrooms. Monomethylhydrazine occurs in the poisonous false morels, which may be mistaken for true morels. See Toxin.

The amatoxins of amanitas cause severe abdominal cramps, nausea, vomiting, and violent diarrhea. Jaundice and cyanosis often develop, followed by coma and death. Symptoms usually become apparent 8 to 12 hours or even longer after the mushroom is eaten; death follows in 2 or 3 days. Treatment for poisoning by amatoxins and muscarine is supportive after the mushrooms have been cleansed from the gastrointestinal tract. Thioctic acid is administered to individuals poisoned by amatoxins, but its effectiveness is uncertain. Atropine is an antidote for muscarine poisoning but not for other poisons produced by fungi.

Amanita is common in open woods, wood margins, and roadside places, from early summer until frost. It is 10 to 20 cm (4 to 8 in) tall, with a cap 10 to 15 cm (4 to 6 in) broad. The cap is scaly and brightly colored, usually orange-yellow to pale yellow. The flesh is yellow just beneath the skin, but the inner flesh is white. The white and scaly stem is bulbous at the base and bears a soft torn frill or ring close to the top. The gills are white or pale yellow. The specific name and the common names are derived from its property of poisoning flies.

The death cup, or death angel, and three related species are the most deadly mushrooms known. Most other amanitas are poisonous or suspect. An exception is Caesar’s amanita, an edible mushroom popular since Roman times.
Jack-o-lantern is a saffron-yellow gill mushroom that grows at the bases of decayed stumps. The stem is 7 to 13 cm (3 to 5 in) tall, and the cap is 7 to 13 cm (3 to 5 in) wide. In shape it bears a resemblance to an edible mushroom of the same genus, the short-stem giant clitocybe, which has a large cap when mature and is white to tan in color.

Many other mushrooms are generally avoided because, like Satan’s mushroom, their edibility is doubtful, or because, like stinkhorns, they have a disagreeable odor. The so-called emetic mushroom and its near relatives should be avoided.

Scientific classification: Mushrooms make up the family Agaricaceae. The species usually grown commercially is classified as Agaricus bisporus, the field or garden mushroom as Agaricus campestris. The chanterelle is classified as Cantherellus cibarius. Pore mushrooms make up the genus Boletus. The king boletus is classified as Boletus edulis, the oyster mushroom as Pleurotus ostreatus, the sulfur mushroom as Polyporus sulfurreus, and the shaggy-mane as Coprinus comatus. Giant puffballs belong to the genus Calvatia; other puffballs make up the genera Lycoperdon and Scleroderma. The true morel is classified as Morchella esculenta. False morels belong to the genus Gyromitra. The Périgord truffle is classified as Tuber melanosporum. Amanitas make up the genus Amanita. The fly amanita is classified as Amanita muscaria, the death cup as Amanita phalloides, and Caesar’s amanita as Amanita caesarea. The jack-o-lantern is classified as Clitocybe illudens, the short-stem giant clitocybe as Clitocybe gigantea, Satan’s mushroom as Boletus satana, and the emetic mushroom as Russula emetica.



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