Ridged tooth (Hydnellum scrobiculatum)

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Hydnellum scrobiculatum
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Ridged tooth fact file

Ridged tooth description

KingdomFungi
PhylumBasidiomycota
ClassBasidiomycetes
OrderThelephorales
FamilyThelephoraceae
GenusHydnellum (5)

The ridged tooth fungus belongs to the stipitate hydnoid fungi group. Members of this group are also known as 'tooth fungi' (fungi that release their spores from tooth-like structures), and all have a short stalk or 'stipe', hence the name 'stipitate' (7). Young fruit bodies of Hydnellum scrobiculatum have different colours to older ones, as the pale area of growth is broadest in young specimens (4). As they age, the fruit bodies become brown with ridged 'growth zones' that radiate out from the centre (4). Several caps often fuse into one mass, which has a number of stalks that may grow around blades of grass and other objects (4). This species shares many features with the very similar Hydnellum concrescens, which is said to be distinguished by being more distinctly zoned, by the flesh greening in alkali, and by its slightly smaller spores (7).

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.

Size
Cap diameter: 3 - 5 cm (1)
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Ridged tooth biology

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 (1).

Hydnellum scrobiculatum is associated with pine trees; this provides an easy, but not necessarily accurate way of distinguishing between this species and H. concrescens, which occurs under chestnut or oak trees (1).

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 protective chemicals that may also protect them from grazing mammals (1).

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Ridged tooth range

The ridged tooth fungus is widely distributed in the northern hemisphere and has also been recorded from Australasia. It has a wide distribution in England and Scotland, but is scarce (4). In England, many records originate from the New Forest (9), East Berkshire, and the Surrey Commons (1). There is one doubtful record from Wales (8).

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

Occurs under pine trees in woodland (1), and other trees including broadleaved species (6).

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Ridged tooth status

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

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Ridged tooth threats

The true status of this species is unclear due to the confusion with H. concrescens. If all records of H. scrobiculatum that were made under species other than pine or 'conifer' were discounted, the species would rapidly become one of Britain's rarest Hydnellum species. 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).

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Ridged tooth conservation

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). Scottish Natural Heritage has been conducting an extensive survey of all stipitate hydnoid fungi in Scotland (4). Ridged 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. The status of this fungus will remain a mystery until some reliable method of distinguishing it from H. concrescens is found. (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.
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Find out more

For more information on British fungus, see:

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Authentication

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/

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Glossary

Ectomycorrhizal
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.
Eutrophication
Nutrient enrichment of aquatic or terrestrial ecosystems.
Fruit body
In fungi, the fruit body is the visible part of the fungus which bears spores (microscopic particles involved in both dispersal and reproduction).
Photosynthesis
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.
Spores
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.
Symbiotic relationship
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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References

  1. National Biodiversity Network Species Dictionary ( November 2002)
    http://www.nhm.ac.uk/nbn/nhm/index.html
  2. Marren, P. (2000) Stipitate hydnoid fungi in Britain. English Nature Research Report No. 420. English Nature, Peterborough
  3. UK BAP Group Action Plan (Nov 2002):
    http://www.ukbap.org.uk
  4. English Nature (1998) The wild mushroom pickers code of conduct. English Nature, Peterborough.
  5. Pegler, D.N., Roberts, P.J., & Spooner, B.M. (1997) British chanterelles and tooth fungi. Royal Botanic Gardens, Kew.
  6. Marren, P. & Dickson, G. (2000) British Tooth Fungi and their Conservation. British Wildlife. 11, number 6 401-409.
  7. Ewald, N. (2001) Survey of the New Forest for stipitate hydnoid fungi. Hampshire Wildlife Trust Report.
  8. Turner, J. (2002) Stipitate hydnoid fungi in Wales. Plantlife Report 208.
  9. Carl Borges (2002) English Nature. Pers. comm.
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Image credit

Hydnellum scrobiculatum  
Hydnellum scrobiculatum

© Gordon Dickson

Gordon Dickson
hydnellum@zoom.co.uk

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