The grey tooth fungus belongs to a group known as the stipitate hydnoid fungi. These fungi share some morphological characters, but are not naturally related (5). They are 'tooth fungi', fungi that release their spores from tooth-like structures. The fruit bodies are terrestrial and have a short stalk or 'stipe', hence the name 'stipitate' (5). The teeth are on the underside of the fruit body (5). The flesh of all members of the genus Phellodon is tough and somewhat leathery; it becomes 'corky' when it dries (5) and develops a distinct spicy smell (6). The caps may fuse together to form one mass with a number of stipes, and may grow around and even engulf blades of grass and twigs. The outer margin of the fruit body is the area of growth, and is paler in colour than the rest of the cap, which is brown with striations radiating out from the centre (6). This area of growth is wider in young specimens; the cap may change as it ages in terms of colour, shape and texture (5), but confusion can arise as the downy surface of the cap can darken greatly when it rains (6).
WARNING: many species of fungus are poisonous or contain chemicals that can cause sickness. Never pick and eat any species of fungus that you cannot positively recognise or are unsure about. Some species are deadly poisonous and can cause death within a few hours if swallowed.
Fungi are neither plants nor animals but belong to their own kingdom. They are unable to produce their own food through the process of photosynthesis, as plants do; instead, they acquire nutrients from living or dead plants, animals, or other fungi, as animals do. In many larger fungi (lichens excepted) the only visible parts are the fruit bodies, which arise from a largely unseen network of threads called 'hyphae'. These hyphae permeate the fungus's food source, which may be soil, leaf litter, rotten wood, dung, and so on, depending on the species. With the exception of the earpick fungus Auriscalpium vulgare, all stipitate hydnoid fungi are ectomycorrhizal species; they form close symbiotic relationships with trees, and derive some of their nutrients from the tree's roots. This aids them in obtaining nutrients on poor quality soil, and means that are always found in association with trees (5).
Like Hydnellum, Phellodon species are often surprisingly free of invertebrate damage. It is thought that they may contain defensive chemicals that repel invertebrates and possibly even mammalian grazers (5).
Widespread in Europe and North America. Rather than 'vulnerable', the status of this species is more realistically described as 'local and not uncommon' (7). It is known from southern England, Scotland, Wales (8), and western Ireland (6); it is one of the most widespread of the stipitate hydnoids in England, but seems to be fairly rare in Scotland (5). In Europe it is rare in Scandinavia but becomes widespread towards the south (5).
This species is associated with a wide range of host trees including oak, sweet chestnut, birch, pine, and spruce (5). It occurs on sandy soils, typically on bare or mossy ground, and its distribution indicates that it prefers warm areas (5).
All species of stipitate hydnoid fungi are vulnerable to the effects of atmospheric pollution (5), soil eutrophication, soil disturbance (eg by timber management) and competition from vascular plants (5).
The UK Biodiversity Action Plan (UK BAP) has produced a Group Action Plan for the 14 species of stipitate hydnoid fungi that occur in the UK (3). A number of sites that support this species, including the New Forest, are Sites of Special Scientific Interest (SSSIs) or reserves (3). The grey tooth fungus is afforded general protection under the Wildlife and Countryside Act 1981, but it is not one of the four species of fungi given special protection under Schedule 8. Much more research on these fungi is needed if they are to be conserved (5); it is unfortunate that fungi are truly 'the forgotten kingdom' when it comes to conservation action (9).
An association between a fungus and plant roots, from which both species benefit. The fungal threads form a sheath around the root. The plant benefits as root uptake is increased as a result, and the fungus receives nutrients from the plant roots.
Nutrient enrichment of aquatic or terrestrial ecosystems.
In fungi, the fruit body is the visible part of the fungus which bears spores (microscopic particles involved in both dispersal and reproduction).
Metabolic process characteristic of plants in which carbon dioxide is broken down, using energy from sunlight absorbed by the green pigment chlorophyll. Organic compounds are made and oxygen is given off as a by-product.
Microscopic particles involved in both dispersal and reproduction. They comprise a single or group of unspecialised cells and do not contain an embryo, as do seeds.
Relationship in which two organisms form a close association, the term is now usually used only for associations that benefit both organisms (a mutualism).
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