Amanita virosa

Amanita virosa, commonly known in Europe as the destroying angel, is a deadly poisonous basidiomycete fungus, one of many in the genus Amanita. Occurring in Europe, A. virosa associates with various deciduous and coniferous trees. The large fruiting bodies (i.e., the mushrooms) appear in summer and autumn; the caps, stipes and gills are all white in colour. Immature specimens of A. virosa resemble several edible species commonly consumed by humans, increasing the risk of accidental poisoning. Small specimens may resemble the common Portobello mushroom to non-experts, but just one cap of A. virosa is enough to kill an adult human. The symptoms of poisoning comes generally several hours afterwards, a fact which makes this fungus even more problematic. Along with its geographical namesakes, A. virosa is one of the most poisonous of all known poisonous mushrooms; its principal toxic constituent α-amanitin damages the liver and kidneys, usually fatally. The common name of destroying angel is applied to several all-white species of poisonous Amanita, to this species in Europe and to Amanita bisporigera in eastern North America, and A. ocreata in the west. A. virosa was first collected and described by Elias Magnus Fries in Sweden. Its specific epithet virosa derived from the Latin adjective virōsus 'toxic' (compare virus). Amanita virosa is very similar to several other species of all-white amanitas known as destroying angels, which has led to confusion over which occurs where. This specific name has been applied to all-white destroying angels occurring in North America, though others propose these all belong to Amanita bisporigera and other rarer species instead. There has been some question over whether Amanita verna is a valid species. Amanita virosa first appears as a white egg-shaped object covered with a universal veil. As it grows, the mushroom breaks free, though there may be ragged patches of veil at the cap edges. The cap is initially conical with inturned edges, before becoming hemispherical and flattening with a diameter up to 12 cm (4 3⁄4 in). The cap often has a distinctive boss; it is able to be peeled and white, though the centre may be ivory in colour. The crowded free gills are white, as is the stipe and volva. The thin stipe is up to 15 cm (5.9 in) tall, with a hanging grooved ring. The spore print is white and the spores egg-shaped conical and 7–10 μm long. They stain blue with iodine. The flesh is white, with a taste reminiscent of radishes, and turns bright yellow with sodium hydroxide. This fungus highlights the danger of picking immature fungi as it resembles the edible mushrooms Agaricus arvensis and A. campestris, and the puffballs (Lycoperdon spp. ) before the caps have opened and the gills have become visible. The ability to be peeled has been taken as a sign of edibility in mushrooming, which is a potentially lethal mistake in this species. It is unclear why this fungus, which more closely resembles edible species, has been implicated in fewer deaths than the death cap, though its rarity may contribute to this. Amanita virosa is found in mixed woodland, especially in association with beech, on mossy ground in summer and autumn. Most Amanita species form ectomycorrhizal relationships with the roots of certain trees.