Tuesday 16 October 2007

Toadstalls


To me, autumn is the season of decay; much of the luxuriant growth of summer is broken down and utilised by a host of unseen organisms. Included with these are the fungi, hidden for much of the year and only now evident as their fruiting bodies push up through the ground. Perhaps the most well-known of the autumn-fruiting fungi is the fly agaric, it’s red cap – speckled with white – instantly recognisable to even the most casual of observers. This is the toadstool upon which gnomes are pictured, which is featured dancing by Disney and which has a folklore extending back into the antiquity of many cultures.

The fly agaric belongs to a genus of fungi known as the Amanita, which contains not only some of the most beautiful fungi but also some of the most deadly. The Amanita are cosmopolitan in distribution and the 30 or so examples in Britain include species that are also found on the sun-bleached hillsides of North Africa and the Arctic tundra of Alaska. The various species typically form close relationships with trees and all of the British species are thought to be mycorrhizal. This means that instead of occurring loosely in the soil, their underground structures (known as hyphal threads) accumulate around tree roots. Some of the threads penetrate the roots and help the fungus to receive moisture and nutrients from the tree; in return, the tree gains an enhanced ability to compete with other plants for soil nutrients. These relationships are complex and this may be why fly agaric is usually found associated with birch and, to a lesser extent, pine, rather than other tree species.

The name ‘fly agaric’ comes from the formerly widespread practice of using the fungus as an insecticide. The chopped fungus would be sprinkled with sugar or placed in milk, killing the flies that it attracted. The main toxic ingredient in fly agaric is concentrated in the red skin of the cap but with ageing, permeates into the cap itself. The toxin attacks the central nervous system causing lethargy and nausea and, depending upon the dose, a hallucinogenic high. As such, fly agaric was regularly used to induce a state of spiritual exaltation in primitive cultures. Needless to say, messing around with such potentially dangerous toxins is not to be recommended, particularly when this group of fungi contains species that can kill. The aptly named death cap has been responsible for 93% of the European deaths caused by fungus poisoning; just half a cap is sufficient to bring about death. Strangely, several members of the genus are edible after cooking but, given the potential costs of a misidentification, I don’t think I will be trying them.

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