14 January 2011

One not for the pot - The Death Cap

We've had a brief respite from the bitterly cold weather that's been hanging around since the end of October, and I've been pleasantly surprised by the amount of fungi I found when I went out earlier this week.  Plenty of Velvet Shanks (Flammulina velutipes), which are to be expected at this time of year, but also some autumn species such as butter caps (Collybia butyracea) and these Mycena inclinata (edibility unknown):

Perhaps, though, I should devote some column-space to a fungus the edibility of which is known all too well, because it's one of the two most poisonous mushrooms on the planet: the Death Cap (Amanita phalloides).  2010 was a record year for mushroom poisonings both in the UK.    This was partly because of the ever-increasing number of people who are going out hunting for edible mushrooms but also because 2010 just happened to be a very good year for both the Death Cap and its equally-deadly cousin the Destroying Angel (Amanita virosa).  

In one high profile case, the Norfolk teenager Lucy Adcock ate two raw death caps, thinking they were common field mushrooms, and was extremely fortunate not only to survive but also to escape serious liver and kidney damage.  Anyone who is thinking of picking wild mushrooms really needs to have an image on these two species burned into their mind: learn these first.  There should be no excuse for confusing them with field mushrooms, because the poisonous Amanitas emerge from a bag (or "volva") and field mushrooms do not.  So you should always check the base of the stem very carefully. 

One of my favourite pictures of the year shows the volva very clearly. It was posted by a member of the public on the website of the Association of British Fungus Groups by a person who, at the time the photo was taken, had no idea what she was holding in her hands (no copyright).  Fortunately she did not eat them, but the picture still makes me shudder.  I don't even like touching these beasties.

The Death cap is a rather variable species, both in cap colour and size.  There is a pure white form, but the cap is normally grey-green.  It can be rather small and delicate or large and chunky like those pictured above.  The key identifying features are the volva and the gills which stay pure white (the gills of the edible Agaricus species turn pink and eventually brown.)  As well as being confused for Field Mushrooms, the death cap has also been eaten in the past by people thinking it was one of the green Russula species or Volvariella gloicephela and very small specimens have even been mistaken for a puffball, which is why beginners should always slice small puffballs in half just to make sure there's no mushroom forming inside. 

One cannot overstate the toxicity of this species.  The two specimens pictured above would be sufficient to kill several people, and it is a horrible way to die.   The initial symptoms are delayed.  A few hours after ingestion the victim suffers severe stomach pains, vomiting and diarrhoea, but these symptoms eventually pass and the person often believes they are going to make a full recovery.  However, the toxins do not pass out of the body.  Instead, they are re-absorbed by the kidneys and cause repeated cycles of damage to the internal organs.  The victim will usually die from liver and kidney failure within days.  

If you are in any doubt at all about your ability to identify these two species, stay well clear of anything that looks remotely like them.