Mealy tooth  (Hydnellum ferrugineum)

Provisionally classified as Endangered in Great Britain (2). Digging up fungi without permission could constitute theft under the Theft Act of 1968 (3).

The mealy tooth fungus belongs to the stipitate hydnoid fungi group, also known as the 'tooth fungi'. Members of this group release their spores from tooth-like structures. The fruit bodies are terrestrial and have a short stalk or 'stipe', hence the name 'stipitate' (1) (8). The teeth are on the underside of the fruit body (1). The flesh of Hydnellum ferrugineum is leathery, tough and becomes corky as it dries. The cap often has an irregular shape (1), and usually displays obvious growth zones that radiate out from the centre (4). Caps may fuse into one mass with a number of stalks, and can grow around twigs, leaves or blades of grass (4). This species is very similar in appearance to Hydnellum spongiosipes, but has paler flesh with more obvious zonations (4).

Hydnellum ferrugineum is found throughout Europe, North America, and North Africa (8). It is widespread but scarce (4) in Scotland (1) and there are old reports from the New Forest (9) and Wales (7).

You can view distribution information for this species at the National Biodiversity Network Gateway.

Found in Scots pine (Pinus sylvestris) woodlands and old plantations on dry soils underneath Scots pine. The association with Scots pine is a major difference between this species and the similar Hydnellum spongiosipes, which has a range of hosts, none of which are pine (1).

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. Trees that have fungal partners have been shown to have a greater up-take of nutrients and trace elements as a result, so both the tree and the fungus benefit from living together in this way (5).

The best time of year to look for the fruit bodies of Hydnellum species is September. Interestingly, all Hydnellum species show very low levels of invertebrate damage; it is possible that they may contain defensive chemicals that protect them (1).

There is no evidence that this species has declined (1); however it is nonetheless scarce and needs attention (1). All species of stipitate hydnoid fungi are vulnerable to the effects of atmospheric pollution (1), soil eutrophication, soil disturbance (eg by timber management) and competition from vascular plants (1).

The UK Biodiversity Action Plan (UK BAP) has produced a group action plan for 14 UK species of stipitate hydnoid fungi (2). Much more research on these fungi is needed if they are to be conserved (1), and Scottish Natural Heritage has been conducting an extensive survey of all stipitate hydnoid fungi in Scotland (4). The mealy tooth fungus is afforded general protection under the Wildlife and Countryside Act 1981, but it is not one of the four species of non-lichenized fungi given special protection under Schedule 8 (2).

There may be further information about this species available via the National Biodiversity Network Gateway.

The UK Biodiversity Action Plan for this species is available at UK BAP.

For more information on the conservation of British fungi, see:

• Association of British Fungus Groups:
  http://www.abfg.org/