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.