availability of materials that they can utilise as fungal food. Some habitats, such as woodlands, contain substantial amounts of potentially available organic matter, whereas others, including the world’s oceans, are less favourable. Despite this, oceans are far from devoid of fungi, although most of the species that can put up with the saline conditions are microfungi.
The average amateur mycologist, especially one with a culinary interest, concentrates on finding fruitbodies of the larger fungi including the agarics (mushrooms and toadstools), bracket fungi, puffballs and morels. For mycologists, knowledge of the habitat requirements of sought-after species is comparable to the way in which botanists and ornithologists are able to predict which flowers or birds they may find when visiting a particular habitat.
Common species of mushroom and toadstool include those that are relatively catholic in their taste, but also those species that are restricted to a specific food source that is itself widely available. Rare species often demand exacting habitat requirements that are themselves uncommon. Other rare fungi may be limited by environmental factors such as temperature or water availability. In Britain the latter group are frequently at the edge of a wider distribution throughout mainland Europe.
Dung roundhead (Stropharia semiglobata) is a very common ‘little brown job’ that grows on the weathered dung of a wide range of herbivores, including cow, sheep, horse and rabbit. It is found in pastures, heaths and even in woodland. It also grows on land fertilised with herbivorous dung and on clifftop grassland, where its normal requirement for animal dung is fulfilled by bird guano.
In contrast, the nail fungus (Poronia punctata), an ascomycete with fruitbodies that are shaped like a nail or golf tee, only grows on horse dung and is virtually restricted in Britain to the New Forest where it grows on dung of semi-wild ponies. It is one of the fungal species with a UK Biodiversity Action Plan (see here). Until the early part of the 20th century horses, their dung and the nail fungus were all common. In the 21st century, even in those parts of Europe, including Britain, where horses are still kept for riding, the fungus is now very rarely found. It appears that the use of additives in horse feedstuffs and the use of artificial fertilisers on the pastures grazed by horses have affected the nature of horse dung, something that has not happened to dung from the less pampered ponies grazing on the largely unimproved land of the New Forest.
Agaric fruitbody emerging through tarmac
{Joe Blossom/NHPA}
Sulphur tuft (Hypholoma fasciculare) is one of the commonest toadstools to be found on the decayed wood of tree stumps, fallen trunks and timber used to make path steps or edging for garden borders. It grows on a very wide range of different tree species, both broadleaved and coniferous; just as its substrate is common so is the fungus. As the common name implies, it grows in dense tufts and, when young, has a sulphur-yellow cap, stem and gills, the latter turning purplish-brown as the spores mature. Sadly, this very frequent fungus is not edible as it has a very bitter taste, comparable to quinine.
Birch polypore (Piptoporus betulinus) is nearly as common as sulphur tuft, despite being restricted to birch trees. This is because birch trees are very common in Britain and the fungus, which is a parasite on living trees, can continue to live as a saprophyte on dead ones. In contrast, oak polypore (Piptoporus quercinus) is rare enough to need protection in a manner similar to that for the nail fungus. It grows on dead wood in the trunks of veteran oaks, usually ancient deer park or forest trees (often over 400 years old) that were formerly pollarded. Unlike young birches, the number of veteran oaks is very limited and so too, as a result, is the oak polypore.
The distribution and frequency of many woodland fungi are strongly influenced by their need for very specific habitats. Fungi that form mycorrhizal associations with tree roots (see here) often do so with only one or a limited number of tree species. Examples include the larch bolete (Suillus grevillei), associated with larch trees, and beech milkcap (Lactarius blennius), which is only rarely found away from beech trees. Some species obtain their food from tree fruits, including ear pick fungus (Auriscalpium vulgare), a small toadstool that grows only on partially buried pine cones. Other more common fungi feed on the discarded leaf litter that is a feature of deciduous woodland. Typical of these is wood woollyfoot (Collybia peronata).
Larch bolete –Suillus grevillei
{Laurie Campbell/NHPA}
Fungi of grassland communities include field mushroom (Agaricus campestris) and species such as yellow fieldcap, previously known as egg-yolk fungus (Bolbitius titubans, was B. vitellinus), which feed on decayed grass leaves, dung and straw. Some 50 species of waxcap (Hygrocybe spp.) are largely restricted to old, unlimed, grazed pasture that has not had inorganic fertiliser added. This is a habitat whose area has declined by over 90% since 1930. Mown, unfertilised old lawns and even some cemeteries are also homes for waxcaps and other species that are unable to compete in grassland where lime and inorganic fertilisers have been applied.
Other habitats that include fungi specific to them include coastal dune systems, where such rarities as the dune stinkhorn (Phallus hadriani) and dune mushroom (Agaricus devoniensis) are to be found. The fruitbodies of dune mushroom develop under the sand, only pushing through as the spores mature; possibly a strategy to cut down on water loss in what is a very dry environment.
A strange group of fungi grows on burnt ground associated with bonfires, forest fires and the controlled or accidental burning of heather moorland. Such ‘phoenicoid’ fungi (as in phoenix-like, literally arising from the ashes) include the beautiful tiger’s eye or brown goblet (Coltricia perennis), a bracket fungus with a mushroom shape that is occasionally used in florists’ displays. Tiger’s eye also grows in other sites, especially on sandy, acidic soil. In contrast bonfire scalycap (Pholiota highlandensis), a brown toadstool, is restricted to fire sites in either woodland or heathland. Despite this limitation it is common and widespread, as are fire sites. It is often found with bonfire inkcap (Coprinus jonesii), which is only rarely found away from burnt ground. Several cup or disc-like ascomycete fungi inhabit fire sites, where the ground may be covered with their fruitbodies. One of these is the stalked bonfire cup (Geopixis carbonaria).
Geopixis is occasionally found protruding from the mortar of garden walls or emerging from damp plaster inside houses. Both these sites are very alkaline (they have a high pH) because of their lime content. The fresh ash resulting from wood or heathland fires is also extremely alkaline, one reason why fresh ash should not be used as a garden mulch. Very few fungi or plants can thrive in such conditions, but it appears that many phoenicoid fungi are adapted to and even thrive in an environment that is toxic to other species.
A relative of Geopixis is even more at home in our homes. Cellar cup (Peziza cerea) produces clumps of delicate, pale buff-coloured, cup-shaped fruitbodies up to 3–4cm across. It grows on damp mortar or earth in moist cellars and erupts from rotting sandbags (an increasingly common habitat in flood-prone areas). It is famous for its association with toilets, where the moist conditions of gentlemen’s urinals, or on a wall or carpet soaked by a leaking cistern may result in large numbers of the fruitbodies. Fortunately, cellar cup does little damage and may even be a useful indicator of the damp conditions on which it thrives. Such conditions may provide a foothold for a much more serious household fungus and one that is not found outside any artificial habitat in Britain; dry rot (Serpula lacrymans) (see here).
Gardens, along with parks, playing fields and churchyards, provide important urban sites for mushrooms and toadstools. Mycorrhizal species (see here) that obtain their food from tree roots are common in gardens and parks, and even on pavements. Earthballs (Scleroderma spp.) frequently burst through tarmac or thrust up between paving stones. Toadstools that are mycorrhizal with garden trees include