Hydnellum concrescens (Pers.) Banker 1906

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 they are always found in association with trees (1). The best time to look for the fruit bodies of H. concrescens is September. Interestingly, all Hydnellum species are very rarely damaged by invertebrates, and it is thought that they may contain certain chemicals that prevent them from being eaten (1).

Much more research on these fungi is needed if they are to be conserved (1). The UK Biodiversity Action Plan has produced a group action plan for 14 UK species of stipitate hynoid fungi (2),(8). Management measures likely to help these species include the preservation of banks within woodlands (1). Many sites supporting this species, including the New Forest, are Sites of Special Scientific Interest (SSSIs) or reserves (2). The zoned 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).

The zoned tooth fungus belongs to the stipitate hydnoid fungi group, also known as the 'tooth fungi'. Members of this group share some morphological characters, but are not a naturally related group (1) (7). They are known as tooth fungi since they release their spores from tooth-like structures. The fruit bodies (the visible part of the fungus) are terrestrial and have a short stalk or 'stipe', hence the name 'stipitate' (1). The teeth are on the underside of the fruit body (1). The flesh of Hydnellum concrescens is leathery, becoming corky when it dries. The cap often has an irregular shape (1), and usually displays obvious growth zones, which form layers (4). Caps may fuse into one mass with a number of stalks, and can surround twigs, leaves or blades of grass (4). 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.

Found in broadleaved woodlands, commons, and parks in association with oak, sweet chestnut, pine, larch and birch (1). It can be found on raised banks, stream banks, managed chestnut coppice and the sides of trackways (1), and shows a preference for open vegetation (6).

A widespread but local species throughout the northern hemisphere, H. concrescens has been recorded from 25 vice-counties of England, 14 of these records being made after 1960 (1). It mainly occurs in southern England, is relatively widespread in the New Forest, and is also found in the Thames Valley (1). It has been recorded from 3-4 sites in Wales (9) and is also known from Scotland and Ireland (8).

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

Comparison of pre-1960 and post-1960 records of H. concrescens seems to indicate that the range of this species in the UK has decreased somewhat; however older records are often very unreliable (1). All species of stipitate hydnoid fungi are vulnerable to the effects of atmospheric pollution (1), soil eutrophication, soil disturbance (e.g. by timber management) and competition from vascular plants (1).