In Ireland you can expect to find up to 5,000 species of mushrooms and toadstools aside from the other types of fungi. Of these, about 25 are good edibles and over 100 are severely toxic. 

Human activities are influenced and affected by Fungi in a surprising number of ways. Not only do we find Fungi on the gourmet’s table as mushrooms or truffles, but they also contribute important antibiotics to the doctor’s medicine chest such as penicillin and streptomycin. One can also mention the important and beneficial role of Fungi in the various industrial processes such as the brewing, baking and dairying industries. Conversely one must also remember the importance of Fungi as agents of disease in plants and animals and in the decay and spoilage of food, fabrics and indeed timber.

To appreciate where and how Fungi fit into the so-called jigsaw of life one must first understand the concept of the “ecosystem”. An “ecosystem” is the sum total of all the living and non living parts that support a chain of life within a selected area. The four primary links in this chain are:

1. Non living matter: the sunlight, water oxygen, carbon dioxide, organic compounds and other nutrients used by plants for their growth.
2. The Plants: ranging in size from the microscopic water-organisms to grasses, shrubs and trees. These plants are collectively called the Producers. They convert carbon dioxide and water in a process called photosynthesis, into carbohydrates required both by themselves and other organisms in the ecosystem.
3. The Consumers: are those organisms that feed on the producers. Herbivores such as cows and sheep are primary consumers. Carnivorous man and other animals feed upon the herbivores and are secondary consumers.
4. The Decomposers: these organisms, bacteria, Fungi and insects, close the circle of the ecosystem when they break down the dead producers and consumers and return their chemical constituents to the ecosystem for re-use by the plants.

The important functions fulfilled by the Fungi as decomposers cannot be over emphasised. Because they are primitive plants devoid of chlorophyll – green colouring matter of higher plants- Fungi cannot use the process of Photosynthesis to manufacture their own food requirements. They must therefore obtain their organic food ready-made. They do this by utilising either dead plants and animal products when they act as saprophytes or by attacking living plants and animals as parasites.

The saprophytic Fungi play a most important and indeed essential role in this intriguing jigsaw of life. They act as scavengers and decomposers and are continuously re-cycling nutrients into the web of life and making them available again for growth. Anywhere there is growth there must be simultaneous decay and decomposition. Were it not the activities of Fungi and other decomposers such as insects and bacteria then, the world would be one vast reservoir of dead animals and plants which would pile up indefinitely. There would be no renewal of the simple nitrogenous and other essential nutrients used by green plants and since plants are the basis of all existence on this earth, life as we know it would only come to an end. It is most important to maintain this delicate equilibrium. Man-made interference such as the widespread and indiscriminate use of pesticides and chemicals disturbs the balance and inhibits fungal and bacterial activity.

Most people know the Fungi as “Mushrooms” or “Toadstools”. These are the reproductive structures (fruit-bodies or sporophores) of a particular group of rather highly specialised and advanced Fungi. They bear large numbers of minute bodies, which are usually single cells, and are known as spores. These become detached and are readily dispersed by wind. If they land on a suitable substrate, and other conditions are favourable, they germinate and give rise to the vegetative phase of the Fungi. This consists of a mass of fine, branched threadlike filaments called hyphae known collectively as mycelium. These hyphae continuously exude enzymes that breakdown and decompose the substrate. A single hypha is too small to be seen by the naked eye but aggregations of hyphae, forming mycelial strands, can be seen and so can the fluffy mass of the mycelium. The mycelia of the various species of saprophytic Fungi ramify in the soil, or among fallen leaves and other organic litter. Under suitable environmental conditions, the cycle is completed when the sporophores are produced from aggregations of individual hyphae.

FURTHER READING

1. Fungi - an introduction: Lilian E. Hawker
   Hutchinson University Library, London
2. Mushrooms and Toadstools: John Ramsbottom
   The New Naturalist Series: Collins London.