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the mighty oak and its mushrooms Many common fungi are found in woodland. There are two types of relationship that can exist between the mushroom and the tree. In northern Europe, where growing conditions may be difficult, certain mushrooms and trees form a mutually beneficial relationship known as ‘mycorrhizal’. The mushroom channels nutrients from the soil into the roots and in return absorbs nutrients from the tree. A parasitic relationship such as that usually found with bracket fungi, is one where the mushroom may eventually kill the tree. Most woodland fungi have a natural affinity for a particular or a group of particular trees. Identifying the type of woodland in which you may be wandering, will certainly provide clues as to the type of fungi to be found there. So which mushrooms are you likely to find under the oak tree? Poor Man’s Beefsteak (Fistulina hepatica), also known as the ‘Oak Tongue’ is one. A bracket fungi or polypore, it is shaped like a liver or tongue and has the colour and texture of raw beefsteak although it is in fact somewhat sour to eat. Parasitic, it causes wood to discolour to a rich dark brown and so rather strangely, is much sought after by furniture manufacturers. The famously delicious, orange Caesar’s Mushroom (Amanita caesarea) and the infamous, deadly Death Cap (Amanita phalloides) are two of the same family found especially in oakwoods. Agrippina, wife to the Emperor Claudius, poisoned her husband by lacing the former with the juice of the latter and thereby established her son by a former marriage, Nero, as the future Emperor. Amanitas are the most dangerous of families and in general are known as the ‘Death Caps’ although with the tree their relationship is mycorrhizal. Most have distinct detachable white patches on the caps, a ring on the stem and a bag, volva or distinct ridge at the bulbous base. All have pure white gills. Two famous bracket fungi, the Artist’s Fungus (Ganoderma applanatum) and the Varnished Conk or ‘Reishi’ (Ganoderma lucidum), frequently infect oak trees. The Artist’s Fungus can be 2 feet across or larger and is light in colour on its underside. It is so named because it turns a dark brown when scratched so that fine drawings can be made with a needle or knife and also dried specimens keep well. The latter polypore like its English name suggests, looks as if it has been beautifully varnished. Known as “ling zhi” in China and “reishi” in Japan, with a host of other names that translate in meaning to indicate a very prized fungi (“spirit plant”, “plant of immortality” etc), it has been used in Chinese and Japanese folk medicine for over 3000 years to treat disorders such as coronary heart disease, chronic bronchitis, hypertension, and cancer. In fact, its beneficial medicinal properties appear to be varied and bountiful although as yet largely unsubstantiated. Even so it is currently used in clinics and is undergoing extensive tests. Often confused with the edible honey mushroom (Armillaria mellea) since both are a light shade of brown and grow in clumps at the base of trees, is the hallucinogenic aptly named ‘Laughing Jim’ (Gymnopilus spectabilis). Belonging to the Brown Gills or Cortinariales, it can be accurately identified by its property of turning green on cooking. But it is a poisonous and dangerous mushroom with a bitter and unpalatable taste. Mainly found associated with oak when in deciduous forests, it can also be found under conifers. The legendary Perigord truffle (Tuber melanosporum) needs no introduction. Round and warty, it lies buried a few centimetres under the soil and is cultivated in association with the oak although in Africa often with the acacia. This is a mycorrhizal relationship i.e one that is symbiotic and beneficial to both the tree and mushroom. Oak seedlings may be inoculated with truffle mycelium by burying them with pieces of truffle. In a good season, a professional truffle hunter and his hound can earn a small fortune provided that the latter can avoid poisoning by rivals. In Northern Europe, the Jack O’Lantern (Omphalotus olearius) grows in clumps at the base of certain broadleaved trees, oak being one of these. In Southern Europe it grows mainly in association with the olive. It is very poisonous and often confused with the much prized Girolle or Chantarelle (Cantherellus cibarius) on account of its lovely orange colour. Like glow-worms, fireflies and a few other mushroom species it is bioluminescent, that is, it emits light. In 1652, the Swedish historian Olaus Magnum, recounted how in the far north of Scandinavia, pieces of rotten oak bark would be placed at intervals in the forest to help wanderers find their way out by following the light. ‘Maitake’ (in Japanese) or Hen of the Woods (Grifola frondosa), is a bracket fungi growing in dense grey-brown fronds that occurs on stumps and roots of deciduous wood, particularly oak. They can reach staggering sizes often weighing over 10 kilos and are prized edibles, tasting vaguely like aubergine. So highly valued in Japan, Maitake collectors never divulge the location of their find and in fact the name ‘Maitake’ meaning ‘dancing mushroom’, may refer to the idea that they danced with joy on finding it. Medicinally it is under test and has been shown to reduce blood pressure and inhibit tumour growth in mice. The Blue-green Clitocybe (Clitocybe odora) is to be found particularly in oak woodland. As its name indicates, it is blue-green, paling to almost white when dry and has a strong aniseed smell, from which its Latin name ‘odora’. It is strongly aromatic and can be used as a condiment or flavouring. The particular group of trees consisting of the Oak, Sweet Chestnut, Hornbeam and Beech can often be found sheltering the much enjoyed (in Europe if not in mycophobic Britain) Penny Bun Boletus or ‘Cep’ (Boletus edulis) and the Summer Boletus (Boletus aestivalis). Also to be found is the poisonous Devil’s Boletus (Boletus satanas). If in deciduous forests the highly prized edible Chanterelle or Girolle (Cantharellus cibarius) and its poor relation, the Black Trumpet or Horn of Plenty (Craterellus cornucopioides), known as ‘poor man’s meat’ in France, often show affinity for the oak. Otherwise they are usually found associated with conifers just like another interesting mushroom to be found here, the popular Spreading Hedgehog with its spiny underside (Hydnum repandum) often seen in French supermarkets. Finally, you are likely to find the Blue-Yellow Russula (Russula cyanoxantha), the most common of all Russula (Brittle Gill) species, which is one of the best to eat within this family and often stored by pickling in vinegar. Mushrooms are Big Business. Of the above mentioned,
those that have been successfully cultivated are the truffle, ‘maitake’
and ‘reishi’. ‘Maitake’ is a very popular
mushroom in Japan vying for the place of favourite with ‘shiitake’
(Lentinus edodes). The rest of those mentioned are simply
gathered from the wild. Mycorrhizal mushrooms that form beneficial
associations with trees are often introduced when establishing tree
plantations and for the sake of the trees with which they are associated,
it is important that they and their host trees be protected and
conserved particularly from the pollution that may be to blame for
their recent decline. |
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