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GENUS: Amanita

Amanita muscaria (Fr.) S.F. Gray—Fly amanita; fly mushroom; fly agaric

Amanita phalloides Fries—Death cap

FAMILY: Amanitaceae—the Amanita Family

Amanitas begin as round or oval buttons covered by a protective layer, the universal veil. The young button mushroom has small and complete gills, cap, and stalk and can be mistakenly identified as edible puffballs, often with deadly results. As the stalk grows the universal veil is torn, appearing on the expanding cap as warts or patches of tissue. If the universal veil is thick or tough, it will be split by the growing cap and stalk. The cap is then devoid of remnants, but a well formed cup, the volva, surrounds the base of the stalk. The volva occasionally remains in the soil when a specimen is collected; therefore, the absence of a basal cup on a specimen may be misleading when attempting to identify the amanitas. The gills are free from the stipe. Spores of the Amanitaceae are entire, smooth, and thin walled. A further microscopic feature is the divergent tissue in the center of the gill; it grows outward from a central strand.

DISTRIBUTION: The amanitas are found singly or in numbers under hardwoods and conifers from the spring through the fall.

PLANT CHARACTERISTICS: A. muscaria: cap: 8-24 cm across, convex or flat bright yellow to orange red, surface rough with white or yellow wartlike spots; gills and stem: white; stem: 8- 15 cm long and 20-30 mm thick; base of stem: bulbous; veil: white and persistent.

A. phalloides: This species is taxonomically complex, and occasionally several species are lumped under this name. The group includes A. verna (Bull ) Quel., A. virosa (Fr.) Quel, and A. bisporiger Atk. Recent evidence suggests that A. phalloides is rare and often confused with the more common A. brunnescens, which also is poisonous. True A. phalloides has a yellowish-green to green cap and white veil and gills; it is deadly poisonous. In A. brunnescens the cap is dark brown; in the deadly poisonous A. virosa the fruiting body is pure white and the cap is devoid of warts.

POISONOUS PARTS: All parts of the amanitas are poisonous.

SYMPTOMS: The characteristic, well-defined symptoms of A. muscaria poisoning may occur within 3 hours after ingestion. They include increased secretions from salivary, lacrimal, and other glands; perspiration; and possible severe gastroenteritis; much watery diarrhea plus retching and vomiting; possible labored breathing; pupils that are rarely responsive; and possible auditory or visual hallucinations or confusion occurring before or during the digestive upset. For A. muscaria, deaths are rare, but in such cases delirium is followed by convulsions, then coma with death from respiratory failure. In some severe cases, the patient may experience a profound sleep lasting a few hours, then awake without symptoms or memory of the illness that preceded.

Symptoms for the more deadly poisonous amanitas include a 10-hour lag period (6-15 hours) before onset of conditions. They begin as sudden, severe abdominal pain, vomiting, and diarrhea. Blood, mucus, and undigested food are present in vomitus and stool. Thirst, anuria, prostration, and restlessness are also present. If quantities of mushrooms are consumed, death ensues in 2 days; more typically the disease lasts 6 to 8 days before death in adults, 4 to 6 days in children. Fever, hematuria, tachycardia, hypotension, rapid volume depletion, and fluid and electrolyte imbalance also may be present.

POISONOUS PRINCIPLES: A. muscaria. The toxins are choline, muscarine, and muscaridine. The LD50 i.v. in mice is 0.23mg/kg. A. phalloides and other deadly amanitas contain amanitine and phalloidine (complex polypeptides). The toxins amanitin and amanin, also present, are highly toxic; the LD50, i.p. in albino mice is 0.1 mg/kg; for phalloidine it is 3 3 mg/g i.m.

CONFUSED TAXA: Among the many species of Amanita, some are deadly poisonous, whereas others are nonpoisonous. Some of the deadly amanitas are rare (A. phalloides) or infrequent (A flavorubescens); some are very common (A. muscaria, A virosa).

SPECIES OF ANIMALS AFFECTED: Humans, all livestock, and wildlife are susceptible.

TREATMENT: A. muscaria: (11a - with 1:2,000 tannic acid or 1:10,000 potassium permanganate) or (11b); (5 – 0.1 to 0.5 mg either IM or IV, repeated as necessary). Atropine sulfate is antidotal.

A. phalloides: Mortality is 50-90%. First empty the stomach, then: (1-1 to 2 tablespoons in H2O): corticosteroids and both peritoneal dialysis and hemodialysis to eliminate toxins and circumvent kidney failure. A high protein diet and intravenous doses of protein hydrolysate may prevent liver damage. Antiphalloidian serum is effective only when administered at the onset of symptoms; (26); thioctic acid, charcoal hemoperfusion, and vitamin C may be useful.

OF INTEREST: Mushroom poisoning can be produced by about 100 of the 2,000 species known. In the U.S., mushrooms of the genera Amanita and Galerina are the common causes of poisoning. Even trained mycologists may confuse toxic varieties with nonpoisonous or edible ones. There are no simple tests to identify poisonous mushrooms, no effective means to detoxify deadly kinds, and no simple rules or characteristics to follow in determining the toxicity of a mushroom.

Some inky cap mushrooms (Coprinus spp.) may produce toxic reactions if alcohol (beer, wine, etc.) is consumed with them. Some mushrooms (Psilocybe spp.) are hallucinogenic, contain psilocybin and psilocin, and are used in illegal drug trafficking.

 

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