Wetenschap - 23 september 2010

Poisonous, bitter or just plain vile

Because August was so wet, there are very many different kinds of fungi in the woods this autumn. Can you eat them? To avoid falling ill, Resource called on Wageningen expert Thom Kuyper for help. So what do you advise, Thom?

'Look, here we have a bay boletus', says Thom Kuyper. 'It is dirty brown in colour and contains more radioactive cesium than other toadstools.' This still stems from the disaster in the Russian nuclear reactor at Chernobyl in 1986, explains Kuyper. 'In Germany at the time, radioactive particles even ended up in deer that ate the toadstools. The boletus still has a bit too much radioactivity, but it tastes good.'
We are on an excursion with Kuyper to look for fungi on the Wageningen 'mountain'. It is estimated that there are no more than fifty people with a thorough knowledge of fungi in the Netherlands. Kuyper is in the top ten. The soil biologist is giving a group of students a guided tour today. I am looking for edible fungi. But I leave the radioactive bay boletus well alone.
Deadly delicious
You need to know what you are picking, says Kuyper, because there are poisonous ones around. Most of them would just make you feel ill, but a few are deadly. In Russia, where people go into the woods in droves every autumn to pick mushrooms, there are many victims. In Italy, another country where picking mushrooms is popular, there are even government controllers to check the contents of people's baskets of mushrooms for poisonous ones. It goes wrong occasionally in the Netherlands too. 'Last year I was called in to a hospital in Apeldoorn, where someone had been admitted who had eaten the fool's webcap. She will be a dialysis patient for the rest of her life.' Kuyper's advice is: never eat mushrooms or toadstools you don't know. He points out a specimen. 'Take that one there: the bulbous fibrecap. Highly toxic.'
Expert Kuyper picks, sniffs at or tastes most of the fungi he comes across. The sulphur tuft is probably not poisonous, but tastes so bitter you wouldn't want to eat it. The common rustgill smells musty, the jelly tooth is as slippery as a jellyfish and the white milking bonnet smells like raw potato. The shaggy ink cap does not taste too good either. Hardly surprising, seeing that its sap is used for ink. There are palatable species of ink caps, says Kuyper, but you really have to know what you are doing. If you eat the common ink cap with an alcoholic drink, for example, you will fall ill. He found that out for himself when he was a student.
The toadstools we come across in the forest all live up to their names. Mycena alcalina has a chemical smell, milk caps exude a white sap, the split porecrust looks like a scab on a branch, and the brown roll-rim has a curled rim like a hat. Collybia peronata, called the 'sharp tough one' in Dutch, is indeed tough and tastes like chili sauce. And laccaria laccata, aka the deceiver, looks just like many other fungi. 'This is a bicoloured deceiver', says Kuyper, ' recognizable by the hint of purple at the bottom of the stalk.'
Verge better than forest
We carry on smelling and tasting fungi that are neither poisonous nor tasty. Many fungi do not have any flavour at all. Then suddenly we stumble upon a wild mushroom. 'That one is good to eat', says our excursion leader. At last. But our joy is short-lived. 'You must cook it first, as it releases a little bit of hydrogen cyanide.' It turns out there are very few tasty toadstools in the forest. Apart from three wild mushrooms, we only come across a couple of old and shriveled oyster mushrooms. 'You don't get many tasty mushrooms in the forest', says Kuyper. There are too many dead leaves and the soil is too nutrient-rich, partly because of all the dogs that are walked here. If you want to find nice chanterelles and porcinis, you are better off looking along barren verges that are regularly mown. 'There are more of them along the Generaal Foulkesweg.'
Kuyper knows practically every species. There is only one toadstool he cannot identify, and he pops that into a box he has brought along to examine under the microscope later.
There are thought to be about five million species of toadstools in the world, of which only five percent have been identified. Even in the Netherlands a new species is occasionally discovered. This year the press reported the discovery of the spectacular octopus stinkhorn. But our expert corrects them: it was already known. 'It is gradually spreading. It is found in about thirty places now.'
The most beautiful fungus on our trip is the amethyst deceiver, which is the colour of red cabbage. Once Kuyper smelled a fungus before he saw it. But then it was the notorious stinkhorn. The one that smelled the nicest was the herby-smelling fenugreek milkcap. No prizes for guessing which herb it smells like.

'Did you know that picking fungi is forbidden in most municipalities?' asks Kuyper at the end of the field trip. The fungi are the property of the owners of woods, verges or gardens. In practice the law is not strictly enforced. But its existence does give nature organizations scope for intervening if, for example, a group of Poles -fervent mushroom-pickers - head for the woods with baskets.
Well, I have given up by now. When I fancy some tasty chanterelles or porcinis I will stick to the Saturday market in Wageningen.
 

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