Dung fungi are highly satisfactory for demonstrating the diversity and morphology of a group of related organisms within a single ecological system, as representatives of most of the major groups of fungi usually grow on dung after a period of incubation. Dung will always produce characteristic fungi whatever time of year it is collected.

Dung is best incubated in a light place, for example on a window sill, in a warm room on layers of blotting paper or other absorbent material. For rabbit-pellets and samples of similar size petri-dishes are ideal, but for cow, horse and similar types of dung large covered dishes such as casseroles or sandwich containers are very good. Samples should not be kept in airtight containers for long periods of time as under such conditions animal life present rapidly breaks down the dung and induces anaerobic conditions. Instead larvae and earthworms should be excluded from the sample as they decompose the dung and inhibit fungal growth but their activity can be reduced, if causing a problem, by spraying the sample lightly with a proprietary fly-kill aerosol.

By keeping the dung under constant observation during incubation a whole succession of fungi can be seen. Thus the first fungi to appear are the moulds which although numerous need a microscope for their identification. The moulds are followed by a series of Ascomycetes (Sporormia & Sordaria with flask-shaped fruit-bodies and Iodophanus, Coprobia and Cheilymenia with disc-shaped fruit-bodies), which are best sought with the use of a powerful hand-lens or a stereoscopic binocular microscope when their full beauty will be revealed. However, because they need the aid of instruments even to see them they cannot be considered larger fungi. The fruit-bodies of the Basidiomycetes are readily seen with the naked eye, but a hand-lens is still very useful for observing features of the cap and stem, particularly the veil characters. The Basidiomycetes usually conclude the succession of fungi found on dung and soon after this state the dung is colonised by mosses and higher plants and later it is fully incorporated into the soil.

Plate 72. Dung-fungi: Cup fungi and allies

[Larger illustration]

Dung is a very useful substrate for studying succession. However, equally interesting results can be obtained from observing the fungi which appear on a stump, colonise a newly laid lawn, or indeed those growing on refuse such as a cast-out rug; microscopic and larger fungi are all to be found.

If the dung cannot be incubated immediately it should be dried quickly, for most dung-fungi will survive such treatment and grow when the sample is remoistened. The blotting-paper on which the dung is placed should be kept moist throughout the incubation period.

One large discomycete (up to 80 mm across) occurring on manure-heaps must, however, be mentioned, this is Peziza vesiculosa St Amans (see [p. 200]); the inner surface of this cup-fungus becomes detached from the flesh at maturity and forms blisters.

(ii) Fungi of bonfire-sites