Dangerous Fungi

Most fungi are harmless to man and some have an excellent flavour, but there are those with deadly properties. Most notorious is the death cap; few mushrooms and toadstools have long been regarded with suspicion. Yet of the 6,000 species recorded in the British Isles less than a score are known to be poisonous, and only a few of these have proved to be lethal. There are some delicious species which few people would even contemplate eating because they look so different from edible mushrooms sold in shops. Perhaps this is just as well, because some ghastly mistakes have occurred. No fungus should be eaten unless you are absolutely positive about its identification.

The infamous death cap, fairly common in the British Isles, is regarded as the most poisonous fungus in the world; all parts of it. Even the spores, are toxic. The cap is usually an olive-green colour, but it can vary from a pale greenish-yellow to light tan. When it first appears it is rounded or egg-shaped, but it later opens out to become almost flat and up to 10cm (4in) across. A ring hangs loosely under the cap like a frill, partially covering the white stem which is 5-10cm (2-4in) tall.

Even just a quarter of a death cap can be fatal to humans. One of its most distinguished victims was Pope Clement VII in 1534. Together with its close relatives, the destroying angel and fool’s mushroom, the death cap accounts for over 90% of all fatal fungi poisonings.

Destroying angel, very similar to the death cap, contains equally lethal slow-acting poison and is said to have killed Emperor Claudius of Rome. Fortunately it is rarely found in the British Isles, although it grows occasionally in broadleaved woodland. It has a white, rather sticky conical cap about 10cm (4in) across, and white gills, and is supported on a slender white stem up to 15cm (6in) long. Which tends to be covered in flaky scales.

The fly agaric is so well-known that it hardly needs description. It is a beautiful species, and a firm favourite of illustrators of fairy tales. However it is poisonous, although not dangerously so unless taken in large quantities. In 1893 an Italian diplomat in the United States ate two dozen fly agarics fpr breakfast, and died the following day after a prolonged bout of violent convulsions. The species gets its name from its former household use against flies. The caps used to be mashed with milk and sugar and the mixture laid out as bait to attract and kill flies.

The fly agaric is a woodland species that appears in autumn, often in large groups and sometimes in rings. Typically it is found under birch trees with whose roots it forms a mutually beneficial relationship involving the exchange of nutrients. But it is also common in coniferous woods and plantations.

When young the cap is round and covered with a soft creamy white membrane or veil. As the fruiting body grows it pushes through the veil, patches of which are left sticking to the bright scarlet cap. As the cap expands and flattens out. The white spots form an evenly spaced pattern, although they are often washed off by rain. The gills and stem are white. It grows up to 20cm (9in) and the stem gently tapers from a swollen base.

Fly agaric contains small amounts of muscarine – a nerve poison – but the major toxins are ibotenic acid and muscimol, which cause headache, tiredness, nausea and intoxication. This latter property has been exploited for centuries by a wide variety of peoples. Several tribes in Siberia, notably the Koryaks, used to eat fly agarics in dried form to induce hallucinations and delirium. Recently. However, this practice has been more or less replaced by vodka drinking.

The panther is similar to the fly agaric but differs in that the cap is a smoky-brown colour. It is rather rare in the British Isles, appearing under deciduous woodland, especially beech. It contains muscarine in much higher concentrations than the fly agaric, and has been responsible for a number of deaths in Europe where it is more common.

The yellow-stainer often causes a violent stomach upset, although some people are immune, and is not fatal-with recovery in a few days. In some years it springs up in abundance and is often mistaken for the edible field mushroom. The cap is white when young, turning greyish towards the centre as it expands to about 10cm (4in) across. The gills mature from pale cream to a chocolate brown colour. To identify the species, cut the base of the stem; if it turns bright yellow instantly, then leave it alone.

The Inocybe species are a large group of fungi, some of which are poisonous. The red-staining inocybe is another species that has often been confused with the field mushroom. With tragic consequences, since its flesh contains a high concentration of muscarine. It appears rather infrequently along grassy paths, in woodland glades and in the shade of beech trees. The cap is up to 8cm (3in) across, whitish or pale brown at first. Gradually staining red where the cap splits with age. The stem is fibrous and rather tough. It is white or creamy brown in colour, but if bruised during handling soon becomes spotted with red patches. The common white inocybe is a widespread poisonous species.

14. November 2011 by Dave Pinkney
Categories: Featured Articles, Woodlands | Tags: , , , , , , , , , , | Comments Off on Dangerous Fungi


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