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Let a hundred creeping thistles bloom!

In May 1887, the Belgian Official Journal published a law obliging all public authorities, landowners and tenants to root out any thistles growing on their properties or rented plots. Later, a somewhat milder version restricted the obligation to four of the twenty or so native and established species: the spear thistle, the marsh thistle, the welted thistle, and the creeping thistle. The law has been under debate for many years now, but it is still in force in all Belgian regions. Many Dutch municipalities and provinces have similar, be it generally less extreme thistle control acts. What on earth did these poor wild plants do to deserve such abuse? They are important food sources for hundreds of insects and other animals, some of which are quite rare. They produce delightful flower heads that can
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The ornate-tailed digger wasp is one of eight Cerceris wasps native to the Low Countries. The larvae feed on solitary bees that have been paralyzed and buried by their mother. Adults feed on nectar and are wild about the flower heads of creeping thistles.

easily compete with the most gorgeous wild and cultivated flowers. They are not poisonous and do not in any way pose a threat to biodiversity, food safety or the welfare of anything or anyone. They prick, that's all. I know from personal experience this can be pretty annoying. Try building a haystack with reaped grass containing dried thistle stalks and leaves! The original law on compulsive thistle eradication predated the advent of herbicides. At the time, farmers and land labourers still did just about everything with their bare hands. Today, even the Boerenbond or Farmers' Union, Belgium's largest and most influential professional association of farmers and market gardeners, acknowledges that the law is out of date and futile. But only as far as the three biennial species of the targeted quartet are concerned. For the creeping thistle, also known as the field thistle or farmers' pest, the organization wants the current mandatory eradication policy to be maintained on farmland and on land that borders fields or meadows. At first sight, this is not unreasonable. Creeping thistles are perennials
capable of vegetative propagation through underground runners that are often several metres long. That makes them far more difficult to control than biennial thistles that only propagate through seeds. Then again, why doesn't the Farmers' Union demand the mandatory eradication of other perennial rank weeds that also reproduce vegetatively, such as couch grass, field horsetail and many other nettlesome plants? Because they are less conspicuous. Because their seeds or spores are far less visible than thistledown carried by the wind. But most of all because they don't prick.

Civil disobedience: Ouch!

Prior to the second half of the 20th century, when tetanus or lockjaw was still prevalent in Europe, the prickly leaves and stalks of creeping thistles probably caused quite a few casualties. In 1887, it had only recently been discovered that this deadly disease is caused by an anaerobic bacterium living in the soil and the intestines of herbivores like horses. By then, however, the link between tetanus, horse manure and tiny but relatively deep wounds had already
been clear for many centuries. According to some sources, the Belgian legislation on thistle control was originally mainly aimed at the prevention of tetanus*. Today, only people that are not or insufficiently vaccinated are at risk. In countries with adequate vaccination programs and not too many religious fanatics or other nitwits, tetanus has become a very rare disease. So no matter how you look at it, mandatory eradication of any species of thistle is – pun intended – pointless. The many millions of euros that municipalities, nature conservation associations and other landowners spend each year on thistle control are money down the drain. Restricting mandatory eradication to the creeping thistle, a nitrogen-loving pioneer plant of disturbed soils that has effortlessly survived over a century of relentless persecution, doesn't make any sense either. Yes, the Farmers' Union will probably find it easier to sell to its rather touchy rank and file than a complete abolition of the law, but it would still be just about as absurd as a prohibition on prohibiting prohibitions. In the garden at 37 Heuvelstraat, for many years now I have been flouting the current law, a
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Females of the species Eriothrix rufomaculata, a tachinid fly, do not have an ovipositor. They simply deposit their eggs in the vicinity of the caterpillars of grass moths and, presumably, other micromoths. The larvae penetrate the caterpillars and feed on their hosts. Adults feed on nectar and honeydew. Little else is known about the biology and ecology of this relatively common species. The poor thing does not even have an English name.

highly recommended act of civil disobedience. In my orchard, a small hay meadow that is cut only once a year, I rebelliously let the creeping thistles grow and bloom. In spite of their reputation, they do not proliferate. Since the meadow is no longer grazed and fertilized by sheep, the soil is slowly but steadily becoming impoverished, giving numerous other wild flowers an opportunity to settle. In fact, in recent years, the number of creeping thistles appears to be dwindling. Eventually, the species may well disappear altogether. When that happens, I'll shed a tear or two and plant a dozen or so artichokes in a perennial border or the kitchen garden. Artichokes, after all, are nothing but pompous thistles.

* Johnny Cornelis and Martin Hermy, Natuurtechnisch distelbeheer – Eindrapport, KU Leuven, 2002.
Depth of field: the button in my brain

My camera is a very basic, in many respects antediluvian digital single-lens reflex or DSLR camera. While it has less knobs and buttons than your average recent DSLR camera, there are still far more than I care for. Since I belong to the dying race of people that read the fucking manual, I know exactly what they are for, how and when to use them, and why I so rarely do. One button that I hardly ever touch anymore, but frequently used when I first
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Mushrooms are a favourite subject of numerous macro photographers. They never run away and, unlike most flowers, sturdier built specimens do not annoyingly sway in the slightest breeze. They are, in sum, ideal to experiment with different depths of field. The composition and the limited DOF make the picture of a cluster of young mushrooms above more captivating and, to my eyes, more beautiful than a photo of the same group that has the entire group in focus. I believe the mushrooms are wood mushrooms, but I'm not one hundred percent sure.

started photographing, is the usually minuscule press button that helps to check the depth of field or DOF of a photograph before you actually take it. When you look through the viewfinder of a single-lens reflex camera – or at the LCD display of a camera with live preview, a function my eight-year-old Canon EOS 400D sadly lacks –, the diaphragm is completely open. The hole or aperture through which your camera sees the world is as wide as possible. The depth of field, the area behind and in front of the subject you focus on that also appears to be sharp, is minimal. When you take a photograph, the smaller the aperture (or the higher the manually or automatically set ƒ-number or ƒ-stop), the larger the depth of field of that photograph will
be. But before you press the shutter button, while looking through the viewfinder or at the LCD-display you won't see the difference. Unless you also press that enigmatic DOF preview button and keep holding it down. The diaphragm will then close to the set ƒ-number. The image you see through the viewfinder or on the LCD-display darkens – less light gets through a smaller aperture –, but you get a pretty good idea of your photograph's
eventual DOF. By changing the ƒ-number while pressing the preview button and keeping the shutter button halfway down, you can even judge the depth of field and the quality of your future photograph at different values. Now isn't that handy?

All in the mind

In the age of analogue or film photography, the depth of field preview button was a useful tool to prevent wasting expensive film and development costs on failed or substandard photos. I imagine mainly amateur photographers made good use of it. Today, however, the once-lauded little button's lost much of its original lustre. After all, taking dozens of digital photographs of the same subject with a different field of depth doesn't cost more than taking just a few or even a single one. Simply pick out the best and delete the rest. It wouldn't come as a surprise to me if it turned out that many amateur photographers of the plug-and-play generation aren't even aware of the existence of the DOF preview button on their semi professional DSLR camera. Who reads manuals these days? That I myself hardly ever use it anymore, is due to the fact that, by now, I am so familiar with my camera and lenses that I can almost unerringly predict the final DOF of a photograph at any chosen ƒ-stop. It's almost as if there's a depth of field preview button in my brain. I see the photograph before I actually take it. The button in my brain, of which there is no mention in the manual whatsoever, works even better than the one on my camera. The virtual image in my mind's eye always remains vividly bright, even at larger ƒ-stops. It took me a couple of years and thousands of photographs to master this feat. But I don't
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At the back of the garden, each autumn several conifer parasols appear. Young specimens can be quite photogenic. Focussing on the nearest mushroom while shooting with a wide aperture (small ƒ-stop) adds an extra dimension to the picture of this twosome. It has more depth.

take pride in it. It just happened, without my being aware of it. It is, however, one of the reasons why I hesitate to purchase a more recent, better camera body with live view and a larger, full-frame sensor. When I finally do, for quite some time the button in my brain will not function properly anymore. And that button is awfully dear to me.
Later, when I'm all grown up

Photography may well be an art, but my photographs certainly aren't. They are to the work of professional nature photographers what the work of a Sunday painter is to that of one of the great masters. I think of most of my photographs as pictures that are not without merit, show some degree of competence and occasionally have modest aesthetic value. They depict life in the garden as it is, unadorned and devoid of all pretentions. But while a Sunday painter will never accidentally create a masterpiece, with some luck, once in a very rare while, a Sunday photographer may produce a photograph that truly appeals to the imagination. It appears to transcend a more or
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The young swallowtail caterpillar in the foreground appears to be looking at a fully-grown version of itself. Because of the photograph's limited depth of field, the background is blurred. The future remains uncertain.

less arresting registration. There seems to be more to it: a vision, a criticism, an insight, a thought, a message, a hidden meaning, an emotion, an idea. This does not in any way make it a work of art – a designation that, nowadays, increasingly lacks any objective basis –, but it does come pretty close. In early September 2010, dozens of swallowtail caterpillars were feasting on the leaves of the winter carrots in my kitchen garden. Though they were clearly present in greater numbers than in previous years, as always they caused little or no damage. What was a bit unusual, however, was that it concerned caterpillars of all ages, from newly hatched to fully-grown specimens. That gave me the idea for the shot to the left. While I had a razor-sharp mental image of the desired result, it still took me at least an hour and dozens of disheartening attempts to obtain it. A swallowtail caterpillar is a delightful model that readily poses and barely moves, but sadly doesn't take directions. Working with two of these unruly models simultaneously was just
asking for trouble. Nevertheless, I eventually succeeded in taking a decent photograph that so closely resembled the perfect image in my head that my heart skipped a beat. Art? You'd never catch me making such a preposterous claim, but it's definitely one of my best photos ever. Imagine if the young caterpillar in the foreground were a human baby and the one in the background its granddad or granny. I bet a photograph like that would get lots of oohs and aahs. Simply convert it to black and white, print it on fancy cold press photo paper, frame it and hang it on the wall. Art? If you say so!
Only once and never again!

"All mushrooms are edible, but some only once." If you've never encountered this wisecrack or a variation on it, you are either a Martian or simply not interested in fungi at all. Whatever the case, the message is clear: Unless you are an expert and really know what you are doing, picking and eating wild mushrooms is always risky business. The truth of the matter, however, is that some species really are perfectly safe to eat only once but never again and certainly not for the rest of your life. Else that life may well turn out to be much shorter than the life expectancy statistics of demographers and insurance companies seem to suggest. Up until 1944, Paxillus involutus, alias the brown rollrim, was generally looked upon as an edible and altogether delicious mushroom. Since some people found it less easily digestible, most experts did advise against eating it raw. But stewed or fried, in large parts of Europe the brown rollrim was considered a delicacy. Consequently, it was frequently found on the menu of
gourmets and mushroom connoisseurs. Then, about an hour after having consumed an exquisite dish of baked P. involutus, Julius Schäffer, a renowned German mycologist, started suffering from severe stomach cramps, diarrhoea and high fever. Two days later, he was admitted to hospital with acute poisoning symptoms. To no avail, alas, for half a month later the 62-year-old gourmand was as dead as a doornail. No doubt the brown rollrim had already caused numerous casualties, but only now it became clear that this mushroom was anything but an innocent treat. After all, an expert like Julius Schäffer would never have been
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The brown rollrim is not poisonous and supposedly delicious. It is, however, advisable not to eat it more than once. Every subsequent meal is a game of Russian roulette with fewer empty chambers than before.

fooled by a poisonous impostor. Nevertheless, for many years following his untimely demise, nearly all mushroom guides still presented the species as a delicacy, be it only after prolonged cooking or stewing. It wasn't until the mid-1980s that scientists discovered that the brown rollrim contains an antigen that can provoke an allergic reaction after each subsequent exposure. The immune system turns against the body's own red blood cells. It attacks and destroys them. Currently, there is no known treatment that definitely does more good than harm. Blood transfusions can be fatal and there is no medication that can halt or suppress the allergic reaction. Meanwhile, it has become clear that P. involutus also contains substances that can damage chromosomes and may even be carcinogenic. The story of the brown rollrim certainly raises questions about the edibility of the somewhat less common wild mushrooms that present-day guides claim to be as innocent as the farmed chanterelles, shiitakes or button and oyster mushrooms that can be found in just about every modern supermarket. I for one am not inclined to take any chances. Not even only once and never again.
Firebugs on emergency rations

26 May 2009. That Tuesday morning, when, still half asleep, my beloved wife opens the vertical blinds of the large, wall-to-wall kitchen window, she can't believe what she is seeing. Overnight, the patio and the garden pond have turned into an overgrown, seemingly impenetrable wilderness. Is she still dreaming? Has she awoken in a B-movie from the first decade of the Cold War? Has the planet been infested and overrun by a mutant or extraterrestrial plant-like life form? Five minutes later, wearing a dressing gown and a bewildered grin, I am standing next to her, staring in utter amazement at a thick wall of branches, twigs and leaves. Jesus, Mary, Mother of God: there's half a tree covering the front yard! I put on my gardening dungarees and safety boots, and, armed with a chainsaw and a
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What is learned in the cradle is carried to the tomb. An adult firebug and a nymph convivially share a juicy fly.

heavy-duty steel anvil lopper, fight my way through the jungle. The mighty trunk of the large-leaved linden tree right next to the house is as straight and firm as ever, but its crown has all the looks of a miserable, post-modern hairdo after a rollercoaster ride. The crowns of the two equally monumental linden trees in the chicken run are also heavily damaged. A fine, sturdy pear tree planted six years before has snapped just above the ground. Like a match stick. "It was awful", my neighbour and friend Rachid recounts. "I woke up from the noise and looked through the window. There were hailstones as big as
ping-pong balls, rattling thunderclaps and continuous lightning. Like broad daylight. The branches of your linden tree appeared to be spinning around. Like a fairground attraction. Terrifying. You guys really slept through all of that?" We did. While an exceptionally violent, massive thunderstorm moved over the region – in meteorological jargon, a supercell closely trailed by a squall line* – we slept the sleep of the innocent. In the north of France, most of Flanders and the south of the Netherlands, the storm wreaked havoc. Belgian authorities later recognized the event as a natural disaster. That evening, watching the news, we gather that we've escaped the worst of it. The house, the garden shed and the henhouse weathered the storm well. We have lost a pear tree, but all the other trees and shrubs survived. Sadly, the broad, conical crowns of the three old linden trees, the pride and joy of our garden, are in terrible shape. Restoring them to their former glory will require drastic pruning. A job for an expert.

No manna from the heavens

In early spring 2010, the linden trees are topped. They will never grow as tall as they used to be. All the lower heavy branches and all those damaged by the storm are removed, together with all the smaller branches and twigs. What is left of each tree's still bare crown, is cut back to about a metre from the trunk. According to the guys from the company we employed, that's the best way to more or less restore the trees and prevent further damage. They look awful, like amputated floor standing candelabra, but it is the only cure. That summer, as a result of the
radical pruning, the linden trees do not blossom and produce no nutlets. Bad news for the firebugs in the garden. To them, the large, globular fruits of the linden trees are what the antics of Paris Hilton are to the tabloids and the paparazzi: gefundenes Fressen. Do they somehow know that, next autumn, there will be no manna from the heavens? They certainly behave like they do. Instead of clustering in their hundreds on the trunks and beneath the crowns of the linden trees, they slowly but surely disperse all over the garden. Even though they are flightless, by the end of the summer of 2010 they are to be found everywhere.
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Forbidden fruit is the sweetest. In 2010, facing a shortage of linden tree nutlets, the firebugs in the garden switch to a diet of all kinds of seeds, carrion, berries and fruits. They develop a fondness for figs.

Moreover, they appear to change their diet. Far more often than before, I catch them sucking out corpses of flies, spiders, grasshoppers and even their own kind. But the fact that the firebugs increasingly turn into scavengers is not the only novelty. While they previously spent just about their entire lives on the ground, they now start climbing the stems and branches of a wide range of plants to feast on unripe seeds and fruits. Figs appear to be irresistible. That year, the Brown Turkey growing against one of the wooden walls of the garden shed is exceptionally productive. But almost every fig I pick shows signs of damage by ravenous firebugs. They've obviously taken a fancy to their emergency rations. Barely four years after that fateful thunderstorm of May 2009, our three large-leaved linden trees are once again looking great and produce thousands of fruits. As yet, however, the firebugs don't seem inclined to switch back to their normal staple food. They have clearly developed a taste for goodies like figs, blackberries, hollyhock seeds and carrion. Kicking the habit hardly ever comes easy.

* Karim Hamid and Jurgen Buelens, De uitzonderlijke onweerssituatie van 25-26 mei 2009, Meteorologica 3, 2009 (PDF).
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