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Edible and Poisonous Fungi |
For some reason, myths about poisonous mushrooms persist. Many Australians, particularly those of British extraction, have a phobia about 'toadstools' and fear being poisoned by eating 'unknown' fungi. In stark contrast, Continental Europeans have long taken an active interest in the culinary qualities of their native fungi, enjoying the flavour of truffles, chantarelles and morels, while the Chinese have enjoyed the oyster mushroom and straw mushroom, and the Japanese have long revered the flavour-enhancing qualities of shi-i-take and its relatives.
For Australians, of British extraction or not, R.V. Southcott puts the matter into stark perspective: 'the edibility of most Australian species of fungi is untested' (Southcott, 1996). The aboriginal population are known to have eaten fungi. The Beefsteak Fungus, Fistulina hepatica, was eaten by Western Australian Aborigines, according to a mid-eighteenth century record (Kalotas, 1996), and the Pitjantjatjara and Pintupi of the Australian Western Desert were known to eat the Native Truffle Choiromyces aboriginum. The Arunta of Central Australia, however, believed that fungi were endowed with evil magic and would not eat them at all (Spencer and Gillen, 1904, quoted in Kalotas, 1996).
There must be many Australian species which are at least as good to eat as their famous European equivalents. Tony Young, amongst several others, has advanced the state of the art in Euro-Australian ethnomycology by offering many organoleptic and culinary insights into the character of our native fungi.
There are three kinds of poisonous fungi:
Let's start with the ones that can kill you. The most important one on a world-wide basis is the Death Cap, Amanita phalloides, responsible for 90% of the deaths attributable to fungal poisoning in the world (Southcott, 1996; p. 298). It seems to have given all other fungi a bad name. Death from this species is painful and unpleasant. There are no symptoms for the first 12 hours or so, then the victim experiences violent stomach pain and gastroenteritis, followed by vomiting and diarrhoea. Then the effects pass, but only for a couple of days. By that time the toxin has smashed its way through the victim's liver and kidneys, giving A. phalloides an unenviable 50% death rate (Southcott, 1996; p. 300). Should you survive, you are likely to have major kidney and liver damage. "The treatment of choice is often liver transplantation" (David Fischer) If you learn to identify only one fungus in your life (no pun intended), this is the one.
More information about A. phalloides is available here
If you want to know about the poisonous principles in the various species of Amanita, try here
There are other Australian mushrooms which have very similar toxins to A. phalloides. These include many species of Galerina, Gyromitra, Lepiota and Cortinarius.
A much larger group of fungi is the ones which will make you very ill. Tony Young makes the point that this may be due to poisons in the fungus, an allergy, or sensitisation (Young, 1994). Some species, notably Paxillus involutus, can cause acute sensitisation, resulting in death in some cases. Amanita muscaria, the Fly Agaric, easily identified by almost everyone from its constant presence in pictures from fairy stories, will cause gastrointestinal upsets, as will many other fungi. It is so easily recognised that poisoning from this species is almost unheard of. Everyone seems to know it's poisonous.
The hallucinatory or psychotropic mushrooms are another group. The most popular of these seems to be Psilocybe subaeruginosa, often known as 'Golden Tops'. While there are obvious dangers to those who drive under the influence of psychotropic mushrooms, some species of Galerina bear a striking similarity to Psilocybe and occur in similar habitats, increasing the possibility of a fatal psychotropic feast. As I said above, some Galerinas have the same kind of toxins as the deadly Amanitas.
There is no magic way to tell if a fungus is poisonous. Not all dangerous fungi taste unpleasant, almost none of them will stain a silver spoon black, only one or two change colour when the flesh is bruised. The only certain way to know if it is poisonous is to identify it.
But so little of Australia's mycoflora has been collected and identified that the chances are good that you could easily be the discoverer of an even more deadly mushroom than the Death Cap. Many Australian species look superficially like popular edible European species. This has resulted in more than a few hospital admissions.
For many Fungimap volunteers, the situation was beautifully crystallised by our founding father, Dr Tom May, who told us that the only mushrooms he ate came from the market!
References
Kalotas, A.C.(1996) Aboriginal knowledge and use of fungi. in: Fungi of Australia. Vol IB. CSIRO:Melbourne, pp. 269-295
Southcott, R.V (1996) Mechanisms of macrofungal poisoning in humans. in: Fungi of Australia. Vol IB. CSIRO:Melbourne pp. 295-313
Spencer, B. and Gillen, F.J. (1904) The Northern Tribes of Central Australia. Macmillan: London
Young, Tony (1994) Common Australian Fungi: A naturalist's guide. NSW University Press: Kensington
from Fungimap News No. 5, June 1997
For those who enjoy collecting and eating wild fungi, the death in Melbourne last year of a man who ate death caps (Amanita phalloides) has shown that care is needed. Only eat wild fungi if you are absolutely sure of the identity of the fungi. The most common cause of poisoning from wild fungi is the yellow-staining mushroom (Agaricus xanthodermus). It is similar in appearance to the field mushroom (Agaricus campestris) and the cultivated mushroom (Agaricus bisporus), but differs in the rather square profile of the cap when young, the strong unpleasant odour (like hospital disinfectant - caused by the presence of phenol in the mushroom) and the yellow stain when the cap or stem is bruised. Old specimens may have brown caps, with the stain not clear, but usually the flesh in the stem base always bruises yellow (best seen by cutting the stem in half and rubbing the cut surface of the stem base).
from Fungimap News No. 5, June 1997
The Victorian Poisons Information Centre, in collaboration with the Royal Botanic Gardens Melbourne, is carrying out a study to identify the species of fungi which are the cause of poisonings. If you are unfortunate enough to consume poisonous fungi, please contact the Victorian Poisons Information Centre (131 126) and they will arrange for specimens of the fungi to be identified, and send you a questionnaire.
email Records can be submitted by email to Tom May -
may@popa.melbpc.org.au.
Last modified on 7 August 2003
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