Identification of the Larger Fungi. Roy Watling
Common Names
INTRODUCTION
The term larger fungus refers to any fungus whose study does not necessarily require more than a low-powered lens to see most of the important morphological features. Using such a term cuts across the existing scientific classification, for it includes the more obvious fungi bearing their spores on specialised reproductive cells called basidia, fig. 5, and a few of those whose spores are produced inside specialised reproductive cells called asci. The term is useful, however, even though it embraces a whole host of unrelated groups of fungi; it includes the polypores, fairy-clubs, hedgehog-fungi, puff-balls and elf-cups, as well as the more familiar mushrooms and toadstools—or puddockstools as they are often called in Scotland. Specimens of all these groups will find their way some time into the collecting baskets of the naturalist when he is out fungus-picking, along with probably a few jelly-fungi and less frequently one or two species of the rather more distantly related group, the morels. The biggest proportion of the finds, however, on any one collecting day in the autumn, when the larger fungi are in their greatest numbers, will be of the mushrooms and toadstools; these are, collectively, more correctly called the agarics.
The early botanists and pioneer mycologists of the nineteenth century recognised the fact that the fungi both large and small are ecologically connected to the herbaceous plants and trees among which they grow, but many mycologists since have tended to neglect these early observations. Although the importance of the fungi in the economy of the woodland, copse, field and marsh is well-known, mycologists and ecologists alike have been rather slow to appreciate that the fungi can be just as good indicators of soil conditions, if not better, than many other plants. Perhaps it is rash to attempt such a treatment as you find here because we know so little of the reasons why a particular fungus prefers one habitat to another. However, it is envisaged and hoped that, if a framework is provided, accurate field-notes can gradually be accumulated and many of the secrets yet to be uncovered explained.
Where to look
Fungi can be found in most situations which are damp at some time of the year. Searching for fungi can begin as soon as the spring days become warm, although even in the colder periods of winter several finds can be made. In summer it gets very dry and this necessitates collecting in damper areas, such as marshes, alder-carrs, swamps and moorland bogs. After a heavy storm in summer, on the edges of paths and roadsides, woodland banks, in clearings in woods and in gardens, fungi can be collected within a few days of the rain, but collecting normally reaches a climax in August-September, the precise date depending on the locality and the individual character of the particular year.
All woodlands are worth visiting, particularly well-established woods with a mixture of trees. Pure pine-woods do not seem to be as good as pine-woods with scattered birch; plantations are often disappointing except after heavy rain or late in the season, even well into November in mild years. Pure birch and beech, the latter particularly when on chalky soils, are excellent areas to visit. Oak is possibly not as good but areas with willow and alder have many unique species. The edge of woods, sides of paths or clearings are usually more productive areas to search in than is the depth of the wood, and a small plot of trees can be much more rewarding than a large expanse of woodland. After some time one is able to judge the sort of place which will yield fungi. Rotten and burnt wood are very suitable substrates for they retain the moisture necessary for growth of fungi even in dry conditions, so allowing fructification to take place.
Grasslands including hill-pastures, established sand-dunes, etc., are often excellent, but of course they are much more dependent on the weather to produce favourable conditions for fungal development than woodland areas where the changes in the humidity and temperature are less extreme; prolonged mist or mild showery weather favour the fruiting of the grassland fungi. Dung in both woods and fields is an excellent although ephemeral substrate; many species of fungi characterise dung whilst others will grow in manured fields, on straw-heaps or where man has distributed the habitat.
Collecting
The collecting of larger fungi should not be considered a haphazard pursuit; careless collecting often results in many frustrating hours being spent on the identification of inadequate material, which is also not suitable after for preservation as reference material. A few good specimens are infinitely better than several poor ones; one is always tempted to collect too much and then collections are inevitably discarded. Always try to select specimens showing all the possible stages of development from the smallest buttons to the expanded caps. Sometimes such a range is not possible and one must be satisfied with either a couple or only one fruit-body.
Carefully dig up or cut from the substrate the entire fungus and handle it as little as possible. A strong pen-knife or fern-trowel is admirable for the job. The associated plants should be noted, especially trees, and if one is unable to identify the plants or woody debris retain a leaf or a piece of wood for later identification. One should note in a field-notebook any features which strike one as of interest, such as smell, colour, changes on bruising, presence of a hairy or viscid surface.
For transporting home the specimens should be placed in tubes, tins or waxed paper which are themselves kept in a basket. The smallest specimen can go in the first, the intermediate-sized forms in the tins or waxed paper and the larger ones laid in the basket or placed in large paper bags; plastic bags are not suitable except for very woody fungi. Thus an assortment of tins, tubes and various sizes of pieces of waxed paper are essential before setting out on a collecting trip. The specimens should be placed in the waxed paper such that they can be wrapped once or twice and the ends twisted as if wrapping a sweet.
Examination
Once home always aim at examining the specimens methodically.
The first necessity is to determine whether the fungus, which has been collected, has its spores borne inside a specialised reproductive cell (ascus) i.e. Ascomycete, or on a reproductive cell (basidium) i.e. Basidiomycete. By taking a small piece of the spore-bearing tissue, mounting in water, gently tapping it and examining under a low power of the microscope this can be easily ascertained. The tapping out is best done with the clean eraser of a rubber-topped pencil. There are several different shaped asci and basidia; the latter structures are more important in our study because the Ascomycetes are in the main composed of microscopic members.
The following procedure is necessary for the examination of your find:—
Select a mature cap of an agaric from each collection, cut off the stem and set the cap gills down on white paper, or if the specimen is small or is a woody or toothed fungus, or consists of a club or flattened irregular plate, place the spore-bearing surface (hymenium) face down on a microscope glass slide. The smaller specimens must be placed in tins with a drop of water on the cap to prevent drying out. Even with the larger specimens it is desirable to place a glass slide somewhere under the cap between the gills and the paper, and if possible to enclose the species carefully in waxed paper or in a tin. Whilst you are waiting for the spore-print to form, notes must be made on the more easily observable features; one is not required at this stage to examine the microscopic characters.
All the characters which may change on drying must be noted immediately, and these include colour, stickiness, shape, smell and texture. A sketch, preferably