Keys to Fungi on Dung

Coprophilous fungi are highly satisfactory for demonstrating the diversity and morphology of a group of related organisms within an ecological system. Representative genera of most major groups of fungi can usually be guaranteed to appear on dung after a period of incubation. There is no shortage of dung in our fields and woods, and this material will always produce characteristic fungi at whatever time of year it is...
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Coprophilous fungi are highly satisfactory for demonstrating the diversity and morphology of a group of related organisms within an ecological system. Representative genera of most major groups of fungi can usually be guaranteed to appear on dung after a period of incubation. There is no shortage of dung in our fields and woods, and this material will always produce characteristic fungi at whatever time of year it is collected.

Dung is best incubated in a light place, for example on a table in a warm room, on layers of moist filter paper or other absorbent material. For rabbit pellets, and samples of similar size, Petri dishes are ideal; for horse 'apples', and larger types of dung, large covered dishes such as glass casseroles, plastic sandwich boxes or yoghurt pots are needed. The top third cut from a plastic lemonade or mineral water bottle fits neatly in a Petri dish, and replacing the screw cap with a cotton wool plug allows aeration and gives adequate height for developing basidiomycetes. Samples should not be kept in airtight containers for any length of time after collection, as in such conditions insects and nematodes tend to break down the dung, and anaerobic conditions which do not favour the fungi rapidly develop. If they cannot be set to incubate soon after collection they can be gently air dried, as most dung fungi will remain alive after such treatment and grow out when the sample is eventually moistened. The absorbent material should be kept moist. Although free water will not allow the best development of ascomycetes, the succession of basidiomycetes appears to vary with the wetness of the dung. Earthworms and insect larvae should be excluded from the samples as far as possible, for they break up the dung too much; activity of the latter can be reduced by spraying lightly with a household insecticide. If space is limited and cultures are kept nearby, it is very important to prevent mite infestation. Containers can be isolated by placing on glass plates lightly smeared with Vaseline, to which an acaricide (e.g. methyl benzoate) can be added.

Fungi are best sought with a stereoscopic binocular microscope, when their full beauty will be seen, but a hand lens or simple magnifier, although less convenient, is sufficient for all but the smallest forms. The larger ascomycetes and most of the basidiomycetes are readily seen with the unaided eye, but the binocular microscope is still very useful for observing the gross features of the veil of the basidiomycetes. Perithecia, apothecia and similar structures can be removed with fine needles or forceps quite cleanly for mounting, initially in water, on slides. Subsequent irrigation with iodine solution will allow any reaction of ascus wall, tip or pore to be observed, and mounting in diluted Indian ink can enhance the visibility of appendages, caudae and sheaths which occur on some spores. Spore discharge in the ascomycetes often occurs from mature asci when material is mounted in water, so mature spores can immediately be seen. Many of the coprophilous toadstools (agarics), because of their small size and/or rapidly deliquescent nature, often do not give spore prints in the normal way, but mature spores can usually be found on the stipe or in natural spore prints formed on the absorbent material on which the dung is supported. For accurate identification the ability to measure the size of spores and other structures will be necessary.........