Scaly tooth  (Sarcodon imbricatus)

The scaly tooth fungus is a member of the stipitate hydnoid fungi group. These fungi share some morphological characters, but are not a naturally related group (9). They are sometimes called 'tooth fungi', since they release their spores from tooth-like structures. The fruit body (the visible part of the fungus) is terrestrial and has a short stalk or 'stipe', hence the name 'stipitate' (1). The teeth are on the underside of the fruit body (1). Sarcodon imbricatus has been the subject of a taxonomic review (11) and it is now thought that most records from Britain may be of the closely related Sarcodon squamosus (4). Both species are fleshy, mushroom-shaped, and entirely brown, with the cap surface breaking up into large scales (9).

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.

Sarcodon imbricatus occurs throughout the northern temperate zone, in North America, Europe, and Asia (9). It is one of the most common stipitate hydnoids in Scotland (10), but is not known in Wales, and seems to be rare in England, where it occurs in Berkshire and Hampshire (12), with some records from Dorset and Breckland (1).

In Britain this species is associated with Scots pine (Pinus sylvestris) (4) and larch (Larix decidua) and occurs in pine wood habitats (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 (6). Sarcodon imbricatus has been used as a dye and as food (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). The range of scaly tooth fungus does seem to have declined since 1960, but it may have been under-recorded (1). It 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. Scottish Natural Heritage is conducting an extensive survey of tooth fungi in Scotland (10). Much more research on these fungi is needed if they are to be conserved (1); it is unfortunate that fungi are truly 'the forgotten kingdom' when it comes to conservation action (7).

For more on the conservation of rare fungi in the UK see Peter Marren's article available from Plant Talk On-line:
http://www.kak75.dial.pipex.com/Pages/26fungi.html

Information authenticated by Carl Borges of English Nature:
http://www.english-nature.org.uk/ and by Dr Peter Roberts of Royal Botanic Gardens, Kew:
http://www.rbgkew.org.uk/