Introduction to fungi

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Fungi form a huge group of organisms, and the ones commonly referred to as mushrooms or toadstools are just the larger ones. These form only a small proportion of the total, but even so number some 3,000 different species in Britain alone! Fungi have a similar structure to plants but have no chlorophyll and for that reason cannot collect energy from the sun like plants, and instead have to draw their strength from plants, and occasionally even from animals. Woodland species, for example, feed off living or dead trees or fallen leaves. What we refer to as mushrooms or toadstools are in fact the fruiting bodies of the fungus, like the apples on a tree, and the permanent structure, known as the mycelium, is a thread-like structure hidden underground or within the material that the fungus lives on.

There is no way of telling the difference between a mushroom, usually meaning an edible fungus, and a toadstool, meaning a poisonous one, other than by learning to recognise the particular species you are looking at. Most fungi families, including the amanita%20family.html">amanita family, which includes the most deadly species, have some species that are edible and worth eating, some that will not harm you but aren't worth eating anyway, and some that will do you serious damage if you eat them. The bolete family, which includes the most prized edible species of all, the cep, also includes one poisonous species.

Many amanitas and boletes grow on the woodland floor and are associated with particular species of tree. This is a symbiotic association, in other words both fungus and tree benefit from it, but another group of fungi, known as bracket fungi, are parasitic, feeding off and sometimes hastening the death of trees without giving them anything in return. The birch polypore is one of the commonest and the sulphur polypore the most strikiong.

Some fungi grow in meadows rather than woods (in fact fungi can be found in almost any habitat you can think of), for example the parasol mushroom or the st georges mushroom. Most of the larger fungi appear in autumn, but a few, including the st georges mushroom, come up in the spring.