Amanita phalloides

It is a large and distinctive fungus, usually with a cap from 5 to 15 cm across smooth yellow to brown with a green tinge and a partial veil, white fine gills and a white 4 to 18 cm stipe (stalk) with a ring and a swollen volva (base). It is found primarily in Europe but also in northern America, underneath oaks and other hardwoods, usually in autumn to early winter. The fungus is mycorrhizal and beneficial to plants.

As the common name suggests it is highly poisonous, responsible for the majority of fatal mushroom poisonings worldwide, notably through its similarity to Volvariella volvacea. It contains two types of toxins spread throughout the mushroom, phallotoxins (phalloidin, phalloin, phallisin, phallicidin) and amanitins (amatin, amanin, amanullin).

In humans the damage is caused by amanitins, cyclic octopeptides that inhibit protein synthesis by binding with RNA polymerase, causing cellular necrosis. Research has shown that the phallotoxins are not active. Around 0.3 mg/kg of amanitins can constitute a lethal dose, damage is often concentrated in the liver and failure of the liver through centrilobular necrosis[?] and vacuolar degeneration is the most common cause of death.

Symptoms do not begin until 6-12 hours after ingestion and include nausea, vomiting, profuse watery diarrhea and abdominal pain, there is a brief rebate after 48 hours or so before symptoms extend to the cytotoxic stage where evidence of the damage to the liver becomes apparent. Around 15% of those poisoned will die in around 10 days progressing through a comatose stage to renal failure, liver failure, hepatic coma, respiratory failure and death. Those who recover are unlikely to regain full health. Early diagnosis can be tricky and treatment is mainly supportive (gastric lavage, activated charcoal, fluid resuscitation) but includes various drugs to counter the amatoxins, including penicillin and cephalosporin[?] derivatives, and can extend to an orthotopic liver transplant.