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Words lie in our way! – Wherever primitive mankind set up a word, they believed they had made a discovery. How different the truth is! – they had touched on a problem, and by supposing they had solved it, they had created a hindrance to its solution. – Now with every piece of knowledge one has to stumble over dead, petrified words, and one will sooner break a leg than a word. (Friedrich Nietzsche)
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Preliminary mush

The French call it
une chaise. The Dutch call it een stoel. In English, that enigmatic amalgam of Romanic and Germanic languages, it used to be called either a chair or a stool. Whenever a language happens to have distinct names for the exact same object or organism, there is a tendency to differentiate between them. The Dutch slaughter and eat schaap. The French slaughter and eat mouton. The English slaughter sheep and eat mutton. They also slaughter pigs, eat pork and are said to behave like swine when invading Southern European holiday destinations like Majorca or Ibiza. Of course, that's just an ugly rumour and, anyway, German tourists are even worse.

Mushy business

All joking aside, humanity's apparent horror of true synonyms and our strong impulse to differentiate and classify probably explains how the word 'stool' became more or less restricted to chairs without backrests, like typical bar, foot or milking stools. It also became a euphemism for the revolting smelly brown stuff everybody produces, doctors examine, nature recycles and – with the exception of what one hopes is a rarer kind of fetishist – nobody in his or her right mind wants to sit or even step in. (In Dutch, by the way, we have a similar euphemism. No doctor will ever ask you for a sample of your stront (shit) or even fecaliën (faeces), but for a sample of your stoelgang or stool-going.) The origin of this particular euphemism isn't hard to reconstruct. For centuries, toilet or commode stools – basically backless chairs with a buttocks-friendly hole in their seat and a removable chamber pot underneath it – were all the fashion. Shitting while sitting on their fancy stools, dukes and duchesses shared the latest gossip, invented new taxes, sentenced subjects to be broken on the wheel, plotted against their rivals and worried about their piles and the ulcers on their genitals. In time, toilet stools were replaced by even more comfortable, often exquisitely sculpted commode chairs with backs and arms. But the euphemism for the contents of the chamber pot obviously stuck, presumably because of generations of physicians making a career out of checking the august bowel motions of the well-to-do for intestinal worms and other signs of good or bad health. But what, you may well ask, does all this have to do with fungi? Bear with me just a little longer and all will be revealed.

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Magic stumbling blocks

Words have the magic property of being able to conjure objects, organisms, diseases, moods, colours, concepts, substances and all kinds of other stuff into being, at least in people's minds. When a child learns a new word, like ball or red or deoxyribonucleic acid, it is obvious that the word refers to something that is real, something you can point at, something that exists in the external world. So why would words like soul, god, karma, fairy, demon or Rudolph the Red-Nosed Reindeer be any different? You know that toadstools exist because, one fine day, mommy pointed at a fly agaric and cried: "Look! Over there! What a lovely toadstool! No, don't touch it! If you do, you have to wash your hands!" You know that mushrooms exist because, that very evening, claiming they are delicious, daddy practically forced them down your throat. So now you have two words for things that look pretty much the same to you. Very confusing! Obviously, they can't really be exactly the same, because there wouldn't be two different words for them if they were, now would there? In the first book of Morgenröthe or Daybreak, Nietzsche states that words are stumbling blocks and adds that, on the quest for knowledge, "one will sooner break a leg than a word". So it is with some apprehension that I am about to embark on a mycological discussion of the difference between toadstools and mushrooms. The last thing I want is a leg in plaster!

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Mushroom or toadstool?

Typical mushrooms and toadstools are the more or less umbrella-shaped sporocarps or fruiting bodies of thousands of species of fungi, visible to the naked eye and often pretty large and spectacular. So what's the difference between them? That sure sounds like an obvious, straightforward question, but it's not. Remember the chair and the stool? Something similar happened here. In Dutch, the common word for an umbrella-shaped sporocarp is
paddenstoel, which means exactly the same as toadstool: a stool that allegedly toads sit on. In French, the common word for the fruiting body of a single species of fungus is mousseron, also known as le tricholome de la Saint-Georges. In English it is called St. George's mushroom. It is edible, very tasty and widespread. The same is true of the sporocarps that the French call faux mousseron (Scotch bonnet) and mousseron d'automne (clouded funnel), though the last one reportedly may cause gastric upsets. Now simply imagine a monolingual native English speaker trying to pronounce mousseron. Got it? There's little doubt that, after the Norman Conquest, a corruption of the French mousseron or a similar Romanic word evolved into the Middle English musseroun and muscheron to end up as a Modern English mushroom in your pizza ai funghi. Along the way, however, the word lost its original meaning. More than likely, the mushrooms on your plate are not one of the French delicacies mentioned above, but the sporocarps of some kind of commercially grown fungus, like button or oyster mushrooms. It is possible that, at first, the word 'mushroom' or its Middle English predecessors only referred to edible sporocarps – in fact, many native English speakers still claim this is the difference between mushrooms and toadstools – but today it is commonly used for the fruiting bodies of many fungi that are unpalatable or even toxic. Fancy a wild mushroom risotto with a selection of freshly picked yellow staining, sweating and Satan's mushrooms? You are welcome to it, but I'll pass, thanks. In contemporary English, the word 'mushroom' is even used for sporocarps that are rarely or never referred to as toadstools, such as brackets, truffles and puffballs. So while mushrooms started out as a couple of very specific toadstools, toadstools apparently ended up as lots of far less specific mushrooms, namely all sporocarps that resemble an umbrella or a one-legged stool and are visible to the naked eye. This is, actually, my position on this issue. It is also where I draw the line. There is a tendency to use the word 'mushroom' as a common name for the entire organism, as opposed to its sporocarps, but I'm not having any of that nonsense. Just like a flower or a fruit is not a plant, a mushroom is not a fungus. Of course, my definition of toadstools as umbrella-shaped mushrooms is about as scientifically sound as referring to Australia as Down Under or calling the sperm cells of male animals seeds. Language evolved tens of thousands of years before science and we are stuck with a plethora of antiquated words and expressions that, scientifically speaking, make no sense at all. In many ways, our dictionaries are graveyards filled with undead concepts, ghastly zombies that haunt us and gnaw away at our brains. But let's leave it at that. No point in risking breaking an arm as well.
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The fabulous kingdom Fungi

In contemporary Dutch, the word
paddenstoel refers to all sporocarps that are visible to the naked eye, including those that do not look anything like a stool. Therefore, strange as it may sound, paddenstoel should only be translated as toadstool when it clearly refers to an umbrella-shaped sporocarp. When in doubt, it is best translated as mushroom. Sadly, just like in English, there is a tendency in the Dutch-speaking world to use the word paddenstoel for the entire organism. So when Natuurpunt, by far the largest and most influential regional nature conservation NGO, claims on its website that Flanders has some 4,000 species of mushrooms, what they actually mean is 4,000 species of fungi that produce mushrooms or sporocarps visible to the naked eye. Such fungi are commonly known as macrofungi. Four thousand sounds like quite a lot, but given that some experts estimate the global number of species of macrofungi at ranging between 53,000 and 110,000 species, it's almost disappointingly small. Macrofungi represent only about ten percent of all fungi. So for each fungus that produces relatively large fruiting bodies, there are nine species of fungi that produce microscopically small sporocarps or none at all, commonly known as microfungi. In other words, the kingdom Fungi probably comprises over half a million to 1.1 million species. Note the discrepancy. If you were to claim that the world population totals four to eight billion people, nobody would take you seriously. But in studies on the biodiversity of our planet, extremely broad margins like this are run-of-the-mill. According to authors that base their estimates on the ratio between the number of species of plants and that of fungi, the kingdom Fungi comprises at least 1.5 million species. Just about the number of all known and scientifically described species of all natural kingdoms put together.

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A cauliflower fungus is not a vegetable

Carolus Linnaeus, the 18th century father of modern taxonomy, classified fungi as flowerless plants in the kingdom Vegetabile. Reasonable enough, since at first sight fungi have a lot in common with plants. They don't run, fly or swim away. They don't have eyes, ears, noses or mouths. Their hyphae resemble roots and many mushrooms are shaped like flowers or tiny trees. Most cookery books still treat edible fungi as plants and in supermarkets you'll always find them in the fruit and vegetable aisle. I'm not saying they belong in the meat department, though they'd certainly be less out of place there. Should vegetarians be concerned? The fact is that Fusarium venenatum, the fungus in Quorn, is more closely related to pigs and cattle than to the wheat and soy in veggie sausages or burgers. In other words, animals and fungi descend from a common ancestor they do not share with plants. If you think about it, it could hardly be any other way. All living organisms need energy. Plants get if from natural or artificial light through a process called photosynthesis. Animals and fungi are not into that; they simply steal their energy from plants. Some species, such as wildebeests and birch brackets, do it directly. Others, such as lions and petticoat mottlegills, do it through one or more intermediate stations.

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A beefsteak fungus is not meat

Fungi and animals are heterotrophic: they live off other organisms. But while most animals are very motile, fungi are sedentary and incapable of spontaneous, independent movement. The cells of animals are surrounded by a thin, vulnerable and living membrane. Those of fungi, like those of plants, are securely encased. Unlike the hard, dead cell walls of plants, however, those of fungi are not made of cellulose but of chitin. Chitin is the tough, indigestible stuff that the exoskeletons of insects and other arthropods, such as lobsters, are made of. It explains why the button mushrooms you eat leave your body more or less exactly like you've swallowed them. Mushroom stool, so to speak. Cooking, stewing or baking makes them slightly less indigestible. The nutritional value of mushrooms is highly debated, but since they are 90 percent water, you really shouldn't worry too much about their effect on your BMI. They also contain carbohydrates, proteins, fats, minerals, trace elements, vitamins and dietary fibres that supposedly promote digestive health. Mushrooms that contain agaritine, such as button mushrooms and shiitake, are best not eaten raw. According to most studies, agaritine is not just mildly toxic but carcinogenic as well. Of course, other studies disagree or minimise the risks. What a surprise! Whatever the case, heating reduces agaritine levels and is strongly recommended by most food safety authorities, such as the
Dutch Nutrition Centre. Just to be safe. Of course, to be perfectly safe, it is best to stop eating altogether. Before you know it, you'll be the healthiest corpse in the morgue.
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Magnificent moulds

The kingdom Fungi comprises both multicellular and unicellular organisms. In English, multicellular microfungi are usually called moulds, mildews or rusts, while most unicellular microfungi are better known as yeasts. As these are mostly linguistic conventions based on little more than superficial characteristics and apparent similarities, one may just as well ignore them. Even though most people are far more familiar with macrofungi like
Amanita muscaria than they are with microfungi like Saccharomyces cerevisiae, this unicellular fungus plays a much larger part in their lives than the archetypal Christmas red, white spotted toadstool. Dos cervezas, por favor! Well, not without S. cerevisiae, for this fungus is essential to the production of beer, wine and leavened bread. S. cerevisiae is simply beer, wine or baking yeast. If not for this formidable microfungus, there'd be no Heineken, Pomerol or Belgian waffles to enjoy. Back in 1996, S. cerevisiae was the first eukaryote (an organism composed of one or more cells that have at least one nucleus containing its DNA) to have its genome completely sequenced. The fungus has nearly 5,800 functional genes, about a quarter of the number of genes in the human genome. According to some sources, S. cerevisiae and Homo sapiens share over 1,300 genes. Other sources claim they share more than 1,800. Some unicellular fungi can form colonies, a trick many unicellular organisms belonging to other natural kingdoms have mastered too. Such colonies may very well have played a central role in the evolution of multicellular organisms. A world-famous colonist in the kingdom Fungi is Penicillium chrysogenum. Without penicillin, the antibiotic this fungus produces, about three quarters of all humans living today would never have been born. At least one of their parents, grandparents or great-grandparents would have prematurely died from some kind of bacterial infection. It's very likely you owe your life to a fungus that accidentally developed in a Petri dish with a bacterial culture, way back in 1928. One thing's for sure: without penicillin, I'd never have survived the severe case of bacterial pneumonia that I caught when I was still in nursery school and this website would not exist. So three cheers for Sir Alexander Fleming!
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Fungi phyla

"Be it known that, waiving all argument, I take the good old-fashioned ground that the whale is a fish, and call upon holy Jonah to back me. This fundamental thing settled, the next point is, in what internal respect does the whale differ from other fish. Above, Linnaeus has given you those items. But in brief they are these: lungs and warm blood; whereas, all other fish are lungless and cold blooded."

These days, at least in my part of the world, even small children already know that whales are mammals. But in 1851, when the most famous whale story of all time was first published, the matter was still under debate. In chapter 32 of
Moby-Dick, Ishmael, the novel's long-winded and discursive narrator, argues that whales are fish. Did Melville share his protagonist's view? I don't know, but it's certainly not impossible. In what follows, Ishmael presents his attempt at a classification of all whale species. According to their size, he divides them into three books (Folio, Octavo and Duodecimo) and several chapters. In the first chapter of the first book (Folio) he introduces the sperm whale, "without doubt, the largest inhabitant of the globe". Talk about starting off on the wrong foot! The sulphur-bottom or blue whale is much larger – 33 versus 20.5 meters and 180 versus 57 tonnes – but Ishmael treats the species in the final chapter of the first book. So what's the connection between Moby-Dick and the kingdom Fungi? First, according to many sources, the largest creature on Earth is not a whale but an over two thousand year old honey fungus of the species Armillaria solidipes. Secondly and more importantly, both the novel and the kingdom Fungi demonstrate that classification is nearly always problematic. Until well into the 20th century, taxonomists had little more to go on than basic anatomical and external features like size, weight, build or way of life. The more similar two species appeared to be, the more closely they were supposed to be related. Similar-looking features, however, often evolved independently. Time and again, natural selection simply came up with more or less the same solutions and adaptations to more or less the same challenges and circumstances. Dolphins have fins, bats have wings, ferns have spores. Today, molecular biology allows scientists to objectively determine the true evolutionary relationship between species. The results are often unexpected and the always somewhat nebulous kingdom Fungi has been in turmoil ever since. From the lowest to the highest level, from subspecies to phylum the kingdom appears to be falling apart. There's no classification agreed upon by all mycologists and the binomial names of some fungi change almost as swiftly as star soccer players change clubs. To a layman this is all very confusing. But then, so is life.

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To cap it all

All mushrooms on this page are the fruiting bodies of fungi that belong to the phylum Basidiomycota and the class Basidiomycetes. Most of them, like the fly agaric above and the yellow fieldcap to the left, are members of the order Agaricales or gilled mushrooms. At least according to the official Belgian Species List and the Dutch Species Catalogue. According to the Dutch site they belong to the class Hymenomycetes, while both Wikipedia and the Index Fungorum, an international attempt to set the kingdom Fungi in order, put them in the class Agaricomycetes. As always on this site, I rely on the Belgian Species List and the Dutch Species Catalogue. Not because their taxonomic trees are in any way superior – who am I to judge that? – but because I happen to live in the Low Countries and, moreover, think it expedient to restrict myself to these comprehensive, multilingual resources that everyone has access to. The classifications of fungi on these two sister sites are largely identical, but there are still some notable differences. While the Belgian site divides the kingdom Fungi into just nine phyla, for instance, the Dutch site recognizes eleven, one of which is rather laconically named Still to be classified. Sounds ridiculous, but it's not. Our inability to neatly classify all living organisms is largely due to their simply messy origins. Evolution is hopelessly sloppy and nature has all the makings of a botched-up job, which is perhaps the best argument against any kind of creationism or intelligent design. Most familiar fungi belong to the phylum Basidiomycota. Some well-known exceptions are different species of truffles and morels that, like S. cerevisiae and most lichens, are members of the phylum Ascomycota or sac fungi. According to and many other sources, Penicillium chrysogenum also belongs to this phylum. Both the Belgian Species List and the Dutch Species Catalogue, however, classify it in the phylum Anamorphic fungi. Just so you know.
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Lichens and slime moulds

Just like butterflies or dragonflies are not flies, slime moulds are not moulds. They are not even fungi. And while many lichens resemble mosses, they are not even plants. So what are they? Every lichen, such as the
common orange lichen to the left, is a partnership between a fungus and green or blue-green algae that looks and behaves like a single organism. Green algae are closely related to plants. Blue-green algae are in fact bacteria of the phylum Cyanobacteria. Like plants and green algae, they are capable of photosynthesis. This is exactly what the fungal partner is after. In return for the nutrients that the green or blue-green algae provide, the fungus protects them from bright sunlight and dehydration. They literally live in its shadow. The fungus also produces acids that help its partner to absorb essential minerals. This kind of reciprocal assistance is called mutualistic symbiosis or mutualism. Both partners or symbionts profit. Since one of the symbionts is always a fungus and all lichens are named after it, their presence in this section of the site is more or less justifiable. Slime moulds, by contrast, are not even vaguely related to fungi. In fact, many of them are not even related to one another. Known collectively as slime moulds, they are a miscellaneous batch of eccentric creatures that give taxonomists a headache. They don't belong anywhere.

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Odd man out

According to the Belgian Species List and the Dutch Species Catalogue, slime moulds, just like lichens, belong to the kingdom Fungi. This superseded classification is based on little more than superficial similarities and doesn't really make sense. It is, however, still prevalent. To date, the only slime mould I have photographed in the garden is Mucilago crustacea. It looks a bit like a jelly fungus or some kind of mould, but it is no more a fungus than bats are birds or lichens are plants. The yucky yellow goo, commonly known as dog's vomit, soon turns chalky white and later fades to black. It is a mobile colony of countless amoeba-like unicellular organisms that are capable of independent movement and hunt bacteria. They are everywhere, but you need a microscope to see them. As a rule they reproduce just like amoebae: they multiply by division. When conditions are right, however, they swarm together and form the slimy, slowly creeping colonies they owe their collective name to. The slime mould eventually produces spores that are spread by animals or the wind and give rise to a new generation of single-celled free-moving organisms. Worldwide, there are at least a couple of hundred and probably over a thousand species of slime moulds. Not only do they not belong to any natural kingdom, they don't even share a direct common ancestor with all other so-called slime moulds. They are usually divided into three groups of presumably related species. Since nobody knows what to do with them, these three groups generally end up in the rubbish bin of the domain Eukaryota: the pseudo-kingdom Protista. The only reason they seem less out of place there is that, in the infernal cacophony of protists, wrong notes simply don't stand out. So why do I present these weirdies in this section of the site? Because it is prevalent. Because it is where most visitors of the site will expect to find them. But mostly: where else?
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The name of the fungus

More than likely, the mushroom in the photograph to the right is a sporocarp of the
field bird's nest (Cyathus olla). In the garden at 37 Heuvelstraat, this common fungus mainly turns up in the vegetable garden plots. Never seen anything like it? That's probably because these mushrooms are barely 12 millimetres in diameter and under 18 millimetres high. It is highly exceptional that I manage to identify such a small and inconspicuous fungus to species level. Even in this case, I may well be wrong. There are several indigenous species of bird's nest fungi and some of them are hard to distinguish. You would think fungi that produce larger mushrooms are much easier to identify, but that is often not the case. Even experts frequently require a microscope and all kinds of chemicals. When all you have to go on is a photograph of a mushroom, identifying a fungus to species level is often impossible. Sometimes, the smell of a mushroom can be decisive. So can its taste, but I'm not too keen on taking a bite out of any unfamiliar mushroom. Not so much because it may be poisonous, but because it is probably crawling with teensy-weensy maggots and other imperceptible vermin. Yuck!

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Back to school

Underneath the cap of the toadstool to the left, in the lower right corner, some field bird's nests can just be discerned. I am pretty confident that the 'large' toadstool is the fruiting body of a fungus belonging to the genus Mycena. A lilac bonnet (Mycena pura), for instance, or a rosy bonnet (Mycena rosea). In Belgium and the Netherlands, several subspecies or forms of M. pura are found and according to some sources M. pura and M. rosea are actually variants of the same species. Under the microscope, they look identical, but they reportedly produce different toxins. Well, when even the experts are confused… In the species gallery this fungus is included as Mycena sp., meaning: this is a species of the genus Mycena that I could not identify to species level. I'm afraid this will be the case for many fungi. The main problem, no doubt, is my lack of knowledge and experience. When I first started documenting the most eye-catching mushrooms in the garden, back in the autumn of 2010, I knew next to nothing about fungi. I soon found out that, for identification purposes, it is essential to photograph them at least once a day and sometimes even at least once an hour. The shape, size and colour of mushrooms can change quickly and dramatically, so it's always a good idea to register their development. Pay special attention to where they grow, measure them, sniff them, break or bruise them to check for discoloration and other characteristics, pick them to make spore prints: identifying fungi is rarely a piece of cake. I am determined to apply myself to it, but it will take me at least ten years or so to photograph, identify and document all species of macrofungi in the garden. I have no idea how many identified and unidentified species this section of the site will eventually comprise, but it certainly won't be as many as the sections Animals or Plants. For now, the section Fungi does not have any subsections and chances are this will remain the case. The downside is that searching by phylum, class, order, family or genus is not possible. The upside is that the species gallery provides an overview of all macrofungi, lichens and slime moulds I've photographed in the garden to date. Simply click on a thumbnail for more information and photographs.
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Sources and links to more information

  • Arne Aronsen, A key to the Mycenas of Norway, page on Mycena rosea.
  • J.J.P. Baars & A.S.M. Sonnenberg, Voedingswaarden champignons en andere paddenstoelen, Plant Research International B.V., 2008 (pdf).
  • Richard Dawkins, The Ancestor's Tale – A Pilgrimage to the Dawn of Life, Weidenfeld & Nicolson, 2004.
  • Daniel J. DeNoon, The 10 Most Important Drugs, article on WebMD, 2004.
  • Diederich, P., D. Ertz, N. Stapper, E. Sérusiaux, D. Van den Broeck, P. van den Boom & C. Ries, The lichens and lichenicolous fungi of Belgium, Luxembourg and northern France, 2014.
  • Howard Hughes Medical Institute, The Genes we share with Yeast, Flies, Worms an Mice – New Clues to Human Health and Disease, 2001 (pdf).
Geraardsbergen, 7 January 2011.
Latest revision: 7 October 2015.