Northern Ireland's Priority Species

Hydnellum concrescens – zoned tooth

Hydnellum concrescens

Hydnellum concrescens (Pers.) Banker
Family: Bankeraceae

This is a mycorrhizal species associated primarily with broadleaf trees. It is one of the ‘tooth’ fungi, so called as they produce spores on spines on the underside of the cap instead of gills.

In brief

  • Only one Northern Ireland record from Cleggan Valley ASSI near Broughshane in County Antrim in 2001

  • Found under oak but in Great Britain associated with oak, beech, sweet chestnut and Scots pine

  • Found in the British Isles between August and November with the Northern Ireland record from mid-October

  • It is a UK Priority Species

  • The main threats to this species are the loss of the trees with which it forms a partnership and poor woodland management.

Species description
There are a number of different genera of tooth fungi. Hydnellum species are marked by a tough or corky fruiting body and dark to brown spines and spore print. H. concrescens is further marked by a brown cap darkening with age and with distinct zones on the cap. The cap has thin flesh and can also have radial ridges spreading from the centre of the cap to the edge. The spines can be pink when young, turning to brown with age. The fruiting bodies can be fused together at the base. If the fruiting body is sliced, it is dark reddish-brown with concentric lines sometimes visible. It can look very like H. scrobiculatum hence, it must also be looked at under the microscope. See below for the differences between these species. In Great Britain, it is the most common species of Hydnellum.

Life cycle
It was recorded in mid-October in Northern Ireland, although in Great Britain it has been recorded from August to November.

Similar species
The corky tough flesh distinguishes it from tooth fungi in the genera Hydnum, Sarcodon or Bankera and the dark spines and spore print from Phellodon. The thin flesh, brown colours, zoned caps sometimes with radial ridges can identify this as either H.concrescens or H.scrobiculatum. The spores of H. concrescens have double, rather than single, crested spines on their spores which are also slightly larger than H. scrobiculatum. It seems that H.concrescens is usually found under broadleaf trees and H. scrobiculatum under pine, but the confusion between these two species in the past means that it is not possible to say if this is always so. Recent DNA work confirmed that these are closely related but different species, at least clearing up this doubt. Old species of tooth fungi are notoriously difficult to identify and it is not worth trying to do so.

How to see this species
This single modern record in Northern Ireland is from Cleggan Valley ASSI near Broughshane in County Antrim in October 2001. It was found on a mossy bank under oak, alongside the lower track that goes through the wood. This seems to be a typical site for this species so similar habitats are potential sites for this species. Relevant access permissions should always be sought prior to visiting any sites.

Current status
In Ireland, there are two pre-1960 records from Kerry and Cork and this modern Antrim record.

Why is this species a priority in Northern Ireland?

  • It is a UK Priority Species

Threats/Causes of decline
As with most ectomycorrhizal species, the main threats are removal of appropriate tree cover, soil eutrophication due to air pollution, soil compaction due to stock pressure (people pressure is unlikely at this site) or a thick understorey of rhododendron, cherry laurel, bramble, ivy or woodrush. However, as it was found right beside the gravel road through the Cleggan Valley wood, any widening of this road could threaten the spot where the observation was made.

Conservation of this species

Current action
There is a UK Species Action Plan for tooth fungi which was published in 1995.

  • The single Northern Ireland site is an ASSI

  • Implementation of the Northern Ireland Habitat Action Plans for Oakwoods, Mixed Ashwoods and Parkland.

Proposed objectives/actions

  • Maintain and monitor existing population

  • Raise awareness with local site managers and other managers of similar habitats

  • Targeted survey at the correct time of year in similar habitats.

What you can do
Some species of fungi can be difficult to identify, but if you are interested, please contact the Northern Ireland Fungus Group for details of how to record fungi. Records can be sent in using online recording forms or by contacting

Further information

Northern Ireland Fungus Group

NBN Gateway

British Mycological Society

UK Biodiversity Action Plan

Pegler, D., Roberts, P. and Spooner, B.M. (1997). British Chanterelles and Tooth Fungi. Royal Botanic Gardens Kew.

Ainsworth, M. (2004). BAP Fungi Handbook. English Nature Research Reports No. 600

Bridge, P. and Panchal, G. (2004). Population diversity and speciation in Hydnellum and Phellodon species. English Nature Research Reports No. 557.

Ewald, N. (2001). Survey of the New Forest for Stipitate Hydnoid Fungi. Hampshire and Isle of Wight Wildlife Trust.

Marren, P. (2000). Stipitate Hydnoid fungi in England. English Nature Research Series No. 420.

Text written by:
David Mitchel

iNaturalist: Species account : iNaturalist World Species Observations database