Death cap

Appearance

The death cap has a large and imposing epigeous fruiting body , usually with a pileus from 5 to 15 cm across, initially rounded and hemispherical, but flattening with age. The color of the cap can be pale-, yellowish-, or olive-green, often paler toward the margins and often paler after rain. The cap surface is sticky when wet and easily peeled, a troublesome feature, as that is allegedly a feature of edible fungi. The remains of the partial veil are seen as a skirtlike, floppy annulus usually about 1.0 to 1.5 cm below the cap. The crowded white lamellae are free. The stipe is white with a scattering of grayish-olive scales and is 8 to 15 cm long and 1 to 2 cm thick, with a swollen, ragged, sac-like white volva . As the volva, which may be hidden by leaf litter, is a distinctive and diagnostic feature, it is important to remove some debris to check for it.

The smell has been described as initially faint and honey-sweet, but strengthening over time to become overpowering, sickly-sweet and objectionable. Young specimens first emerge from the ground resembling a white egg covered by a universal veil, which then breaks, leaving the volva as a remnant. The spore print is white, a common feature of ''Amanita''. The transparent spores are globular to egg-shaped, measure 8–10 μm long, and stain blue with iodine. The gills, in contrast, stain pallid lilac or pink with concentrated sulfuric acid....hieroglyph snipped...

Naming

The death cap was first described by French botanist Sébastien Vaillant in 1727, who gave a succinct phrase name "''Fungus phalloides, annulatus, sordide virescens, et patulus''", which is still recognizable as the fungus today. Though the scientific name ''phalloides'' means "phallus-shaped", it is unclear whether it is named for its resemblance to a literal phallus or the stinkhorn mushrooms ''Phallus''.
In 1821, Elias Magnus Fries described it as ''Agaricus phalloides'', but included all white amanitas within its description. Finally in 1833, Johann Heinrich Friedrich Link settled on the name ''Amanita phalloides'', after Persoon had named it ''Amanita viridis'' 30 years earlier. Although Louis Secretan's use of the name ''Amanita phalloides'' predates Link's, it has been rejected for nomenclatural purposes because Secretan's works did not use binomial nomenclature consistently; some taxonomists have, however, disagreed with this opinion.

''A. phalloides'' is the type species of ''Amanita'' section Phalloideae, a group that contains all of the deadly poisonous ''Amanita'' species thus far identified. Most notable of these are the species known as destroying angels, namely ''Amanita virosa'' and ''Amanita bisporigera'', as well as the fool's mushroom ''''. The term "destroying angel" has been applied to ''A. phalloides'' at times, but "death cap" is by far the most common vernacular name used in English. Other common names also listed include "stinking amanita" and "deadly amanita".

A rarely appearing, all-white form was initially described ''A. phalloides'' f. ''alba'' by Max Britzelmayr, though its status has been unclear. It is often found growing amid normally colored death caps. It has been described, in 2004, as a distinct variety and includes what was termed ''A. verna'' var. ''tarda''. The true ''Amanita verna'' fruits in spring and turns yellow with KOH solution, whereas ''A. phalloides'' never does.In general, poisoning incidents are unintentional and result from errors in identification. Recent cases highlight the issue of the similarity of ''A. phalloides'' to the edible paddy straw mushroom, ''Volvariella volvacea'', with East- and Southeast-Asian immigrants in Australia and the west coast of the United States falling victim. In an episode in Oregon, four members of a Korean family required liver transplants. Of the 9 people poisoned in the Canberra region between 1988 and 2011, three were from Laos and two were from China. This misidentification is a leading cause of mushroom poisoning in the United States.

Novices may mistake juvenile death caps for edible puffballs or mature specimens for other edible ''Amanita'' species, such as ''Amanita lanei'', so some authorities recommend avoiding the collecting of ''Amanita'' species for the table altogether. The white form of ''A. phalloides'' may be mistaken for edible species of ''Agaricus'', especially the young fruitbodies whose unexpanded caps conceal the telltale white gills; all mature species of ''Agaricus'' have dark-colored gills....hieroglyph snipped...

In Europe, other similarly green-capped species collected by mushroom hunters include various green-hued brittlegills of the genus ''Russula'' and the formerly popular ''Tricholoma flavovirens'', now regarded as hazardous owing to a series of restaurant poisonings in France. Brittlegills, such as ''Russula heterophylla'', ''R. aeruginea'', and ''R. virescens'', can be distinguished by their brittle flesh and the lack of both volva and ring. Other similar species include ''A. subjunquillea'' in eastern Asia and ''A. arocheae'', which ranges from Andean Colombia north at least as far as central Mexico, both of which are also poisonous.

In January 2012, four people were accidentally poisoned when death caps were served at a New Year's Eve dinner party in Canberra, Australia. All the victims required hospital treatment and two of them died, with a third requiring a liver transplant.

Distribution

The death cap is native to Europe, where it is widespread. It is found from the southern coastal regions of Scandinavia in the north, to Ireland in the west, east to Poland and western Russia, and south throughout the Balkans, in Italy, Spain and Portugal, and in Morocco and Algeria in north Africa. In west Asia it has been reported from forests of northern Iran. There are records from further east in Asia but these have yet to be confirmed as ''A. phalloides''.

It is ectomycorrhizally associated with several tree species and is symbiotic with them. In Europe, these include hardwood and, less frequently, conifer species. It appears most commonly under oaks, but also under beeches, chestnuts, horse-chestnuts, birches, filberts, hornbeams, pines, and spruces. In other areas, ''A. phalloides'' may also be associated with these trees or with only some species and not others. In coastal California, for example, ''A. phalloides'' is associated with coast live oak, but not with the various coastal pine species, such as Monterey pine. In countries where it has been introduced, it has been restricted to those exotic trees with which it would associate in its natural range. There is, however, evidence of ''A. phalloides'' associating with hemlock and with genera of the Myrtaceae: ''Eucalyptus'' in Tanzania and Algeria, and ''Leptospermum'' and ''Kunzea'' in New Zealand. This suggests the species may have invasive potential.

By the end of the 19th century, Charles Horton Peck had reported ''A. phalloides'' in North America. In 1918, samples from the eastern United States were identified as being a distinct though similar species, ''A. brunnescens'', by G. F. Atkinson of Cornell University. By the 1970s, it had become clear that ''A. phalloides'' does occur in the United States, apparently having been introduced from Europe alongside chestnuts, with populations on the West and East Coasts. Although a 2006 historical review concluded the East Coast populations were introduced, the origins of the West Coast populations remained unclear, owing to the scantiness of historical records. A 2009 genetic study provided strong evidence for the introduced status of the fungus on the west coast of North America.

''Amanita phalloides'' has been conveyed to new countries across the Southern Hemisphere with the importation of hardwoods and conifers. Introduced oaks appear to have been the vector to Australia and South America; populations under oaks have been recorded from Melbourne and Canberra and Adelaide, as well as Uruguay. It has been recorded under other introduced trees in Argentina and Chile.
Pine plantations are associated with the fungus in Tanzania and South Africa, where it is also found under oaks and poplars.

Habitat

The death cap is native to Europe, where it is widespread. It is found from the southern coastal regions of Scandinavia in the north, to Ireland in the west, east to Poland and western Russia, and south throughout the Balkans, in Italy, Spain and Portugal, and in Morocco and Algeria in north Africa. In west Asia it has been reported from forests of northern Iran. There are records from further east in Asia but these have yet to be confirmed as ''A. phalloides''.

It is ectomycorrhizally associated with several tree species and is symbiotic with them. In Europe, these include hardwood and, less frequently, conifer species. It appears most commonly under oaks, but also under beeches, chestnuts, horse-chestnuts, birches, filberts, hornbeams, pines, and spruces. In other areas, ''A. phalloides'' may also be associated with these trees or with only some species and not others. In coastal California, for example, ''A. phalloides'' is associated with coast live oak, but not with the various coastal pine species, such as Monterey pine. In countries where it has been introduced, it has been restricted to those exotic trees with which it would associate in its natural range. There is, however, evidence of ''A. phalloides'' associating with hemlock and with genera of the Myrtaceae: ''Eucalyptus'' in Tanzania and Algeria, and ''Leptospermum'' and ''Kunzea'' in New Zealand. This suggests the species may have invasive potential.

By the end of the 19th century, Charles Horton Peck had reported ''A. phalloides'' in North America. In 1918, samples from the eastern United States were identified as being a distinct though similar species, ''A. brunnescens'', by G. F. Atkinson of Cornell University. By the 1970s, it had become clear that ''A. phalloides'' does occur in the United States, apparently having been introduced from Europe alongside chestnuts, with populations on the West and East Coasts. Although a 2006 historical review concluded the East Coast populations were introduced, the origins of the West Coast populations remained unclear, owing to the scantiness of historical records. A 2009 genetic study provided strong evidence for the introduced status of the fungus on the west coast of North America.

''Amanita phalloides'' has been conveyed to new countries across the Southern Hemisphere with the importation of hardwoods and conifers. Introduced oaks appear to have been the vector to Australia and South America; populations under oaks have been recorded from Melbourne and Canberra and Adelaide, as well as Uruguay. It has been recorded under other introduced trees in Argentina and Chile.
Pine plantations are associated with the fungus in Tanzania and South Africa, where it is also found under oaks and poplars.

Defense

As the common name suggests, the fungus is highly toxic, and is responsible for the majority of fatal mushroom poisonings worldwide. Its biochemistry has been researched intensively for decades, and 30 grams , or half a cap, of this mushroom is estimated to be enough to kill a human. In 2006, a family of three in Poland was poisoned, resulting in one death and the two survivors requiring liver transplants. Some authorities strongly advise against putting suspected death caps in the same basket with fungi collected for the table and to avoid touching them. Furthermore, the toxicity is not reduced by cooking, freezing, or drying.