Fungi is thriving in the wet

5:43pm Friday 17th November 2000

THE warm, wet spring and wet autumn have resulted in ideal conditions for wild fungi. Caps, cups, earth balls and stars, representatives of this most interesting group of static organisms, are poking up above ground almost everywhere you look, particularly along the woodland margins.

Percentage hydrogen (Ph) is how science expresses the level of acidity or alkalinity in the soil. In our area, two soil types predominate alkaline chalk and acidic boulder clay.

The chalk dates from the Jurassic and Cretaceous periods. The acid boulder clay with flints was deposited over the chalk bedrock at the end of the last Ice Age, being the remnants of rocks ground to paste by unimaginable weight and pressure exerted by the ice sheets that ground their way south then retreated north again during two million years of fluctuating climatic extremes lumped together under the blanket title of the last Ice Age.

It was a fascinating period. Virtually all the northern hemisphere, as far south as the Mediterranean in Europe and the Great Plains of America and central Asia, was remodelled. Mountain ranges of softer rock were planed away and other hard rocks carved into steps or worn into the characteristic U-shape that denotes a glacial valley.

In our region, the ice and subsequent floods that came at the end of this climatic period eroded the covering over the chalk and, in its place, was left a layer of thick, gluey clay that protected the chalk from further erosion.

In the valley bottoms, thick carpets of sand, gravel, clay and chalk slurry developed into the fertile soils that support woodland, marshland and natural meadows.

Alkaline chalk and acid clay make interesting bedfellows. Mixing them together cancels out the main differences, leaving a relatively neutral soil Ph ideal for plant growth.

Thousands of years of farming have turned the chalk with the clay and, more recently, certainly since the end of the Second World War, more than a million or so allotment holders and gardeners have added various soil "improvers" to try to create the perfect conditions to grow vegetables and flowers.

However, in most woodland, where the soil structure is undisturbed, bands of sweet chalk and acid clay lie side by side, overlaid by leaf mould broken down by the thread-like root systems of tens of thousands of fungi and moulds. These organisms (and I use the word "organism" in preference to "plant" because the huge army of fungi and moulds, yeasts and bacteria, of which there are more than a million species, are totally different in structure to members of the plant kingdom) are more closely related to the higher orders of life.

Fungi contain proteins similar to those found in insects, particularly the nitrogenous compounds in the fungi fruiting body.

With a few exceptions, the fruiting body is the part of the organism we have come to regard as being the "fungi". We see them standing like small umbrellas in the woods, or pushing their delicate caps through pavements and asphalt paths and are amazed at their diversity.

Some of them are incredibly beautiful, others are repellent or destructive. such as the dry rot fungus or the honey fungus, which kills trees and spreads like an insidious plague. The stinkhorn fungus, shaped like a phallus, emits a disgusting smell like rotting meat to attract bluebottles and other flies, which collect the sticky spores on their feet and spread them to other parts of the wood.

Several fungi use this strategy but most of them depend on rain or wind blowing along the woodland rides to distribute the spores. The delicately flavoured field mushroom is one that needs the wind in its gills to spread its spores far and wide.

Every year, people venture out into the countryside looking for fungi for the table. Personally, I wouldn't recommend this practice for a number of reason, mainly because of the difficulty of being absolutely certain which fungi are edible (even some of the edible varieties can bring on an allergic reaction) and which are poisonous.

Having led Fungus Forays for a number of years, I'm continually amazed at the way people who would normally never let a doubtful piece of meat or fish pass their lips, will handle and taste all manner of fungi.

I'm sure I can detect a murmur of protest among those that regularly eat wild fungi. In answer. I would say the highest levels of fungal poisoning are found in countries such as France and Poland ,, where gathering wild fungi is a national pastime (it's even possible to have your "catch" identified at the local chemists). My other concern is the damage caused by over-collecting the fungal caps, the seed bank of the fungus.

Fungal spores may be counted in millions but they must drop into just the right growing conditions in order to develop and create the huge underground network of roots that will eventually produce a new crop of fruiting bodies.

They need an association with other plants or trees if they are to reach maturity and, in turn, the trees and plants need the association with the fungi. Fungi break down dead plant material and present it in a form that other plants and trees can use.

This is why you will find only certain species of fungi in certain types of woodland. The boletus and fly agarics are a prime example. The former need beech woods and the latter needs a close association with birch trees.

The supreme fungi, the truffle, is an underground fruiting body. On the continent, it is so highly prized for its ability to impart a special flavour to food it is "hunted" with dogs. In the Perigord region of France, specially trained pigs are used to seek out and uproot the most prized specimens.

Nature designed it to be eaten. The wild boar, ancestor of the domesticated European pig varieties, evolved the nose to root out the ripe spore-packed truffle and, although there would appear to be little benefit to the truffle, this marvellously adapted member of the fungal clan has a trick or two to play.

The spores have the ability to resist the animal's powerful digestive juices and pass through unharmed, dropping onto the woodland floor and creating a fertile growing medium clever things, fungi.

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