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Electronics may be my subject these days but I have a dark secret. As
an undergraduate I studied botany – and became one of the worst students
ever to scrape through the botany school at Oxford. In the practical section
of the final examination, I even fell for the examiner’s time-worn trick
of substituting cotton wool for fungus. But that has never hampered my taste
for mushrooms nor the idea of picking free breakfast delicacies from the
grassland on Hampstead Heath near my home.

Of more concern to me was an apocryphal tale I heard some time ago about
a German family at the end of the Second World War who used to collect fungi
from a wood near their home. To be on the safe side, they always gave some
to the cat and waited until the next day before eating any themselves. If
the cat was still perky, they tucked in. On one occasion, however, the family
was already tucking into a mushroom stew when the cat, who had seemed perfectly
healthy after its taste, suddenly went into convulsions. In a panic, everyone
stuck fingers down their throats to make themselves sick. Soon afterwards
the cat had kittens.

The message is clear, but the problem for me is that I don’t have a
cat and my wife is very attached to the dog. So, at long last, this mushroom
season I resolved to fill some gaps in my botanical education. I made a
pilgrimage to Alston in Cumbria, where the Barhaugh Hall Study Centre holds
its annual ‘fungus foray’ course. Patrick Harding, lecturer in biological
sciences in the division of continuing education at the University of Sheffield,
spends a weekend in and around the centre, a refurbished manor house set
in wood and grassland, telling people how to distinguish between edible
and poisonous fungi. And, yes, Harding told a similar pregnant cat story.

But as Harding went on to explain, the fact that an animal can safely
eat something should never be taken as proof that it is safe for humans.
Maggots, slugs, squirrels, badgers and snails may safely nibble fungi that
will kill a human – just as rabbits may eat the berries of deadly nightshade,
which can be fatal to humans, without suffering any ill effects.

And novice forayers should not be misled into judging the safety of
a fungus by the apparent harmlessness of its colour, smell, taste or shape.
The most beautiful can be deadly, and the ugliest can be harmless or even
a prized delicacy. Species of Morchella, popularly called morels, smell
mealy and look like tiny human brains but they are safe and taste wonderful.

To add to the confusion, many of the safest species look similar to
the most dangerous. There are about 15 edible species of Agaricus, popularly
known as mushrooms. But one of them, the large horse mushroom (Agaricus
arvensis), looks like the yellow stainer (Agaricus xanthoderma), which causes
sickness for a couple of days. Also, both grow in circular groups, or ‘fairy
rings’. The way to tell the difference is either by smell – the horse mushroom
smells like aniseed, the yellow stainer like ink – or by bruising the cap
or cutting the base of the stem and observing yellowing in the yellow stainer.
Though the chanterelle (Cantharellus cibarius) is safe, the false chanterelle
(Hygrophoropsis aurantiaca), which looks similar, contains a ‘bad trip’
hallucinogen and sometimes causes sickness.

According to folklore, poisonous fungi blacken a silver spoon when cooked,
whereas edible ones will not; cooking makes dangerous fungi safe, as it
does for rhubarb and kidney beans; and the skin of edible fungi always peels
easily. But nature has never heard of these rules. The lethal death cap
(Amanita phalloides) does not blacken silver and is just as deadly after
cooking as it is before. The aptly named beechwood sickener (Russula mairei)
peels easily, but still makes people very ill.

For a novice, selecting any species of Amanita is like playing Russian
roulette. The colourful fly agaric (Amanita muscaria) contains a variety
of chemicals, some that cause illness and others that are hallucinogenic.
The trouble is that to enjoy the ‘highs’ but not the ‘lows’, you have to
drink the urine of someone who has eaten the fungus. This is because the
chemicals that cause sickness and liver damage are broken down in the body
while those that generate a feeling of leaving the ground – the archetypal
‘trip’ – pass unaltered in the urine. The warty cap (Amanita rubescens),
or blusher, is edible after cooking but is uncomfortably similar to the
panther cap (Amanita pantherina), which is very poisonous even when cooked.
Caesar’s mushroom (Amanita caesarea), however, is a delicacy though seldom
found in Britain. The grisettes (Amanita vaginata and fulva) are edible
but are definitely an acquired taste, while the destroying angel (Amanita
virosa) looks tempting but is truly deadly. Only occasionally are dangerous
fungi so helpfully named. The weeping widow (Lacrymaria velutina) is common
and edible, so is the trompette de mort (Craterellus cornucopioides), also
known as the horn of plenty.

The amethyst deceiver (Laccaria amethystea) is purple and many of the
wax caps, or hygrocybes, come in exotic colours that suggest danger. In
fact they are edible. But the brown roll-rim (Paxillus involutus), which
is poisonous, sometimes looks like the large brown chanterelle. The saffron
milk cap (Lactarius deliciosus) is an odd yellow colour and seeps orange
milk and bruises green – enough to make anyone suspicious, though in fact
it is safe. On the other hand, the woolly milk cap (Lactarius torminosus)
looks a lot more welcoming but is poisonous.

Opinions vary on the need to cook before eating. After many years of
experimenting, Harding says that cooking is a wise precaution for the popular
cep (Boletus edulis) and an essential one for its cousin (Boletus luridus).
Poor man’s beefsteak (Fistulina hepatica), which grows from the side of
oak or sweet chestnut trees, is edible but is better boiled first to get
rid of the tannin.

WHAT’S YOUR POISON?

Harding has a general rule for all experimenters. ‘Try a small portion
first, don’t mix species and keep some spare. Then if you are ill, you will
know which was the culprit.’ Once fungus forayers understand the full scope
of nature’s conspiracy to poison, while rewarding the skilled with free
delicacies, they begin to appreciate that accurate identification is the
key to survival – or at least a tasty meal. They also recognise how difficult
it can be.

The appearance of a fungus changes considerably over its lifespan. There
are at least 3000 species in Britain alone. Even the book that is arguably
the most helpful guide for beginners, Mushrooms and Other Fungi of Great
Britain and Europe, by Roger Phillips (Pan £12.99), contains less
than 1000 photographs. Many captions refer to ‘edibility unknown’ or ‘said
to be edible’. Others advise caution because of the risk of confusion. ‘Don’t
worry,’ said one regular fungus forayer on a trek through the fields and
woods of Hertfordshire, ‘the first 10 years are the most difficult’.

In many major cities in continental Europe there are up to 30 cases
of serious poisoning by fungi every year, and several deaths, after people
have visited the countryside and picked what they thought were edible varieties.
In Britain, the Department of Health keeps no official records on fungus
poisoning or deaths. The job is left to the National Poisons Information
Service, founded in 1963 and now with eight regional centres in major city
hospitals in Britain. But the statistics of the NPIS give only an indication
of the scale of the problem because each regional centre records only those
victims referred to it. And the figures from each centre are not collated.
The control centre of the NPIS, run by Guy’s Hospital in London and serving
about two-thirds of Britain’s population, dealt with 1669 enquiries on fungus
poisoning between 1983, when it introduced a computer database, and 1988.
Since then calls from the medical profession – the service is not available
directly to the public – have averaged around 400 a year.

At least a third of all cases involve young people who have picked ‘magic
mushrooms’ (Psilocybe semilanceata), or ‘sillies’, in search of a hallucinogenic
trip. They either eat too many or, in optimistic ignorance, pick anything
small and brown that is growing in grassland. Sometimes they end up eating
species of Inocybes, which contain the same poison as the fly agaric. Other
times they eat something innocent, such as the explicitly named dung roundhead
(Stropharia semiglobata), and enjoy an imaginary high. The NPIS centre in
London believes that on average there is less than one accidental death
a year. But, as one doctor admits, ‘I can’t say how many people may be bumping
off relatives with toadstools’.

This may not be just a joke. In her novel The Documents in the Case,
crime writer Dorothy L. Sayers weaves a tale around the death of a character
who thinks he has picked and cooked some warty caps but may have mistakenly
eaten some poisonous fly agarics, which are both species of Amanita. If
he had found the right mushroom, could his food have been maliciously spiked
with the poison present in the agaric? And would forensic analysis show
up the difference between natural and synthesised fungus poison?

Unhelpfully, nature has ensured that the more serious the poisoning,
the longer the symptoms take to appear. So there is less likelihood of the
victim associating cause and effect and having good specimens available
to show a doctor. John Henry, consultant physician with the NPIS in London,
has analysed the behaviour patterns of the poisonous fungi. He says that
the psilocyin and psilocybin contained in magic mushrooms act within an
hour; the muscarine in Inocybes and Clitocybes, and the muscimol contained
in fly agaric and panther cap take a little longer.

It is the coprine found in the common ink cap (Coprinus atramentarius)
that causes trouble when the eater also drinks alcohol. It behaves like
the drug Antabuse that is used to treat alcoholics by causing violent nausea
and diarrhoea after alcohol has been drunk.

The amatoxins in some species of Amanita, Galerina and Lepiota take
at least six hours to show an effect. Then the symptoms seem to disappear.
But the poisons are in fact destroying the liver. This is how the death
cap tricks its victim. By the time the danger is recognised, it may well
be too late. Also the victim will probably have thrown away the remains
of what he or she has eaten. Likewise, orellanin, found in species of Cortinarius,
may take a week to act, by which time the kidneys have been damaged.

One particular horror story concerns three campers in Scotland. They
thought they had found a chanterelle, a fungus with deep ridges replacing
gills, and yellow spores. Instead, they had picked and eaten a poisonous
species of Cortinarius (Cortinarius speciosissimus), which has rusty brown
spores. This dangerous fungus has a tell-tale cortina, a cobweb-like veil
under the cap, but the veil is clearly visible only in young specimens.
The unpractised eye will miss the traces that remain on older specimens.
The price of this mistake was a kidney transplant for two of the campers.

In 1980, the University of Strathclyde commissioned the Royal Botanic
Gardens in Edinburgh to build a computer database of poisons based on medical
symptoms such as dilation of the eyes, blood content and kidney behaviour,
analysis of the stomach content after pumping, half-eaten meals and even
dustbin relics. The botanic gardens planned to offer this database as an
online source of information. Hospitals around Britain would use a personal
computer and modem to interrogate the database by telephone line.

‘We concentrate on identifying the chemical which has caused the problem,’
says Roy Watling, senior principal scientific officer at the botanic gardens
in Edinburgh. ‘If the mycologists want to argue about what species of fungus
it was, they can do that later.’ The database is available on computer
disc, but online access never caught on. There was insufficient interest
from the medical profession, says Watling.

‘On the whole we are very lucky in Britain,’ adds Henry, ‘because people
here are still very wary of picking and eating what they do not recognise.
I call it mycophobia.’ But this pattern is now set to change for the worse.
Over the past year interest in eating unfamiliar fungi has snowballed. During
last autumn’s season, newspapers and magazines, programmes on radio and
television, and even in-flight entertainment on long-haul aircraft told
of the delicious treats, free for the picking, in the countryside. They
are there, all right, but much of the recent media coverage has been frighteningly
superficial.

‘Autumn heralds the arrival of fungi,’ wrote Anton Edelmann, matre chef
of the Savoy Hotel in the Daily Mail newspaper earlier last year. ‘People
can be seen trekking through dewy fields in search of wild mushrooms that
pop up from the ground overnight. The hunt is fun but the consumption can
be even better.’

When I was trying to buy the Phillips book recently I found the only
copy in the shop being read by an American. ‘I am trying to recognise something
I ate yesterday,’ he explained.

Harding says the most comprehensive book, even one that shows several
views of each specimen at different times in its life, cannot illustrate
everything likely to be found. Also the more comprehensive the book, the
more daunting the process of identification is to a beginner. The only safe
approach is structured classification. The pupil must learn basic rules,
rather than try to remember what specific species look like. It takes longer,
but is safer.

Watling too stresses the dangers. ‘Although only a few species are poisonous,
it is too easy to make dreadful mistakes. The public has been brought up
to recognise plants by obvious characteristics. But fungi don’t keep to
classic outlines. They are so variable in colour and shape that colour pictures
in a book just do not translate to the outside world. Unless you work with
them, or regularly go on forays, you just don’t appreciate their plasticity.’

He has seen people who think they have found the highly desirable parasol
mushroom (Lepiota procera), when they have picked other, poisonous species
of Lepiota. Every year he helps panicking parents whose children have picked
haymakers – varieties of Panaeolus, small brown toadstools that grow in
lawns. Some of these contain psilocybin that, though not lethal, makes children
dizzy and sick.

One important, but easily overlooked, aspect of identification is recognising
that different fungi have specific foods and habitats. When there is any
doubt, the collector must make a written note of whether the specimen was
found in grassland or woodland, and, if the latter, the species of tree.
Even this still presents traps for the unwary. A mycorrhizal fungus, which
coexists with a tree’s roots, can send up a fruiting body 50 metres from
the nearest tree – the extent of the root system – and thus appear to be
a field species.

Touch can help with identification. Some fungi are naturally dry and
others are slimy, while Russula fungi crumble between your fingers. Taste
can help too, even with poisonous varieties. Just spit it out, and eat a
peppermint to counter the nasty aftertaste. Some fungi, such as species
of Lactarius, ooze milk. Others, such as the yellow stainer, change colour
when handled and oxygen gets in.

Using the colour of the cap of a fungus as an identifying mark is less
reliable because it may change after rain or with the age of the specimen.
And if you rely on the colour of the spores to help with identification,
you should remember that it is not necessarily defined by the colour of
the gills. The only safe way is to put the specimen on glass or blue paper
– no fungus produces blue spores – and wait a few hours for the spores to
discolour it.

Safe practice is not for the impatient, who would be wise to note the
old adage: ‘There are plenty of old mushroom hunters and plenty of bold
mushroom hunters, but there are no old, bold mushroom hunters.’