Recognising the Death Cap Mushroom

Last week several Amanita phalloides, known commonly as Death Cap mushrooms, were spotted by staff of the National Herbarium of Victoria growing in a park near the Royal Botanic Gardens, Melbourne, reminding us all that during Fungi Season those in southern Australian states should be cautious about the appearance of Death Caps.

David Catcheside, Creative Commons CC-BY-SA. Amanita phalloides.

Sadly, at least six people have died and at least twelve have fallen ill from eating Death Cap mushrooms in Australia in the past decade. Due to Death Cap's similarity in appearance to an edible straw mushroom that grows in China (Volvariella volvacea), victims have been particularly common in Chinese and South-East Asian communities. Volvariella volvacea is not known to grow wild anywhere in Australia.

The Death Cap Mushroom is widespread under oak trees in southeast Australia, but there is concern among mycologists and toxicologists that it may develop the ability to grow in association with other trees, particularly Australian natives, and thereby spread dramatically.

How to Recognise the deadly Amanita phalloides:

Atlas of Living Australia, Distribution of Amanita phalloides as of April 26 2013.

It has a yellowish to greenish cap, sometimes brownish (typically olive-green in the centre and becoming yellowish-green towards the margin) and white, free gills. The white central stem usually has a ring, and at its base there is a large, membranous, cup-like volva.You can see the cup-like volva at the base of the mushrooms in the photo above, where it has been excavated from the soil. If you pull up the specimen to check out this characteristic, do so carefully - preferably using gloves - and wash your hands thoroughly afterwards.  

Amanita phalloides usually grows on its own or in sparse groups below oak trees (Quercus spp.), but has on rare occasionas also been spotted in large groups. It is found in southern Australian states from southern Western Australia through to New South Wales, but its territory may be expanding. A map of known sightings is above.

It has a white spore print. To take a spore print, place the the cap (or a piece of cap) gills down on a black  piece 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 Smooth White Parasol Leucoagaricus leucothites has no green colour in the cap and no volva. Common Rosegill Volvariella speciosa has no green colour in the cap, no ring and a pink-brown spore print.

 Further excellent information on how to identify the Death Cap can be found on the Australian Botanic Gardens website here: http://www.anbg.gov.au/fungi/deathcap.html .

Even if you don't suspect it to be a Death Cap, note that there are many other poisonous mushrooms in Australia!  

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