Poisonous fungi

Agaricus Xanthodermus – Yellow Stainer

 

Edible fungi – R.V. Southcott, one of Australia’s greatest doctor-naturalists, puts the matter starkly:

the edibility of most Australian species of fungi is untested (1996).

Fungimap does not encourage eating wild Australian mushrooms because so little is known about their edibility and many poisonous species are virtually indistinguishable from safe varieties.

A safer and more interesting way to enjoy mushrooms is to learn how to grow your own. Fungimap does not offer any specific advice about doing this, but Forest Fungi has courses for growing mushrooms at home and offers classes to beginners and sells spawn and other supplies for growing your own mushrooms.

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. His book, A Field Guide to the Fungi of Australia, is available for purchase from the Fungimap Bookstore.

Poisonous fungi – there are three kinds of poisonous fungi:

  • Ones that will kill you
  • Ones that will make you seriously ill
  • Ones that will give you hallucinations

The most deadly is the Amanita phalloides – Death Cap, responsible for 90% of the deaths attributable to fungal poisoning in the world (Southcott, 1996; p. 298).  Death 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. If you learn to identify only one fungus in your life, this is the one.

Here’s how to recognise the deadly Death Cap:

  • a yellowish to greenish cap, sometimes brownish (typically olive-green in the centre and becoming yellowish-green towards the margin)
  • white, free gills
  • white spores
  • a white central stem usually with a ring
  • at its base there is a large, membranous, cup-like volva
  • it usually grows on its own or in sparse groups below oak trees (Quercus spp.), but on rare occasions has also been spotted in large groups.

Warning: if you pull up a specimen to examine it, do so carefully, preferably using gloves, and wash your hands thoroughly afterwards.  

It is found in southern Australian states from southern WA to NSW, but its territory may be expanding. .

To take a spore print:  Place the the cap (or a piece of cap) gills down on overlapping black and white pieces of paper and leave it for two to three hours. The gills will drop enough spores to give you a coloured print, and if it shows up white against the black paper that is a good indication – taken together with the other characteristics – that it is a Death Cap.

Look-alikes: The similar-looking Leucoagaricus leucothites – Smooth White Parasol has no green colour in the cap and no volva. Volvopluteus gioicephalus – Common Rosegill has no green colour in the cap, no ring and a pink-brown spore print. Further excellent information by the Australian Botanic Gardens on identifying the Death Cap is here.

Read here the Fungimap blog post on recognising Amanita phalloides.

Other Australian mushrooms have very similar toxins to Amanita phalloides, including Galerina, GyromitraLepiota and Cortinarius.

A much larger group 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 – 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 easy to recognise so poisoning from this species is almost unheard of. Apparently everyone knows 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 above, some Galerinas have the same kind of toxins as the deadly AmanitasMoreover, for many species of hallucinatory mushrooms there is a fine line between ingesting an amount that will produce hallucinations and ingesting an amount that could cause serious organ damage or even death.

There is no sure way to tell if a fungus is poisonous. However, there are many popular (and dangerous) myths about poisonous fungi.

Here are the facts: 

  • 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
  • an animal (including your dog) is just as likely to try a poisonous mushroom as a non-poisonous one
  • the only certain way to know if it is poisonous is to identify it

But so little of Australia’s fungi have 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.

The 2012 Fungimap Festival debate

This debate titled ‘Eating wild fungi: Fun or Foolhardy?’ highlighted the challenges in connecting a population that is predominantly urban-dwelling with the natural environment and explored the potential mismatch of cultural knowledge about wild food developed in one part of the world (such as Europe), when transplanted to distant localities (such as Australia).

To argue for the Fun side were Patrick Jones, forager and poet, Graeme Phillips, food writer and Alison Pouliot, fungi photographer and educator. On the Foolhardy side were poisons experts, Dr Tom May and Dr Teresa Lebel and mycologist Dr Genevieve Gates. (By the way, Dr Tom May, Senior Mycologist at the Royal Botanic Gardens, Melbourne, Fungimap founder and likely person consulted if you to call Poison Control in Victoria, only eats mushrooms he has purchased from the supermarket!)

Both teams provided well argued and at times hilarious reasons, and some agreement was reached that people need to know more about fungi!

The audio is here and see Patrick’s blog here

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


Watch out for Yellow Staining Mushrooms

from Fungimap News No. 5, June 1997

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) (photo above). 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).