Fomes fomentarius (L. ex Fr.) Kickx- Hoof Fungus

Phylum: Basidiomycota - Class: Agaricomycetes - Order: Polyporales - Family: Polyporaceae

Fomes fomentarius - Hoof Fungus

Tinder Fungus and Hoof Fungus are two common names for the persistent, tough polypore Fomes fomentarius. This large bracket fungus attacks mainly birch but occasionally beech and sycamore. The pale leather-brown flesh was used for lighting fires (it burns very slowly); for this reason it was given the name Tinder Fungus.

Distribution

Rare in southern Britain and Ireland; common in Scotland and northern mainland Europe.

Fomes fomentarius - Hoof Fungus on a Poplar in southern France

Trout fishers use to carry chunks of dried Hoof Fungus, with which they would dry their artificial flies to make them float. Called 'amadou', the material was specially treated and had the reputation of acting as a very effective desiccant.

This is one of the bracket fungi found among the possessions of Otzi the Iceman, a 5000 year old man whose body was preserved in a glacier in the Ötztal Alps on the border between Austria and Italy, where it was discovered by hikers in 1991. It seems likely that Otzi was carrying this material in order to light a fire at the close of a day whose end he did not live to see.

Otzi's mummified corpse is currently on display at the purpose-built South Tyrol Museum of Archaeology in Bolzano (South Tyrol, Italy).

The brackets of Hoof Fungus shown on the left were growing on an ailing poplar tree in southern France. Poplars can live for several years with this fungal attack, but gradually the trees are weakened until they can no longer survive. Soon after a tree dies the brackets of Hoof Fungus cease growing, but they can remain and attached to the dead trunk intact for a year or more.

The dark Hoof Fungus on the left was growing from a fallen Silver Birch in Cambridgeshire, England.

Fomes fomentarius - Hoof Fungus on a Poplar in Cambridgeshire, UK

Taxonomic history

As you might expect with such a common and conspicuous bracket fungus, Hoof Fungus did not escape the notice of Carl Linnaeus, who described it scientifically in 1753 and gave it the name Boletus fomentarius. In 1821 Elias Magnus Fries endorsed the basionym, renaming this bracket as Polyporus fomentarius. The new genus Fomes was erected by Fries in 1849, and the Flemish mycologist Jean Jacques Kickx (1842 - 1887) transferred Hoof Fungus to that genus in 1867, thus establishing its currently-accepted scientific name as Fomes fomentarius.

Synonyms of Fomes fomentarius therefore include Boletus fomentarius L.and Polyporus fomentarius (L.) Fr.

Fomes fomentarius is the type species of the Fomes genus.

Etymology

Fomes, the generic name, comes from Latin and means 'tinder', and rather tautologically the specific epithet fomentarius translates to 'used for tinder'.

Identification guide

Hoof Fungus on a fallen Beech trunk

Fruitbody

This sombre fungus usually appears as a solitary specimen but occasionally two or more tiers are produced.

On standing timber this bracket sometimes gains a hold in clefts in the trunks of older trees; however, the aged specimen shown on the left was found on a fallen beech tree.

Hoof Fungus on a Silver Birch trunk

Annual layers of tubes build up to produce a large hoof-shaped structure 10 to 40cm across and up to 20cm deep at the centre of the attachment line. After the first three or four years, brackets increase steadily in thickness but do not grown much in diameter - hence the resulting hoof shape.

The upper infertile surface is various shades of grey, often with a brownish growing zone towards the outer edge. The lower (fertile) surface is white or greyish, turning slightly brown when bruised.

Pores of Fomes fomentarius

Pores and Tubes

Inside the fruitbody the flesh is hard and pale brown, while the tubes are pale grey-brown at first but become darker brown with age. The pale spore-bearing surface is noticeably softer and has minute pores typically spaced at 2 to 3 per mm.

 

Spores

Oblong-ellipsoidal, smooth, 15-20 x 5-7μm.

Spore print

Very pale lemon.

Odour/taste

The odour is faintly fruity; the taste acrid.

Habitat & Ecological role

Parasitic on broadleaf trees, particularly birch and less often beech and sycamore, but continuing to grow for many months as a saprobe on dead/fallen trunks. I have just once seen Hoof Fungus on a Cork Oak, and that was in the Algarve region of southern Portugal.

Season

Present all year round; shedding spores in late spring and summer.

Similar species

Could be confused with some of the Ganoderma bracket fungi, although they release brown spores; also possibly with Piptoporus betulinus, the Birch Polypore, an annual bracket which has a much smoother upper surface.

Fomes fomentarius - Hoof Fungus on a Poplar inAviemore, Scotland

Culinary Notes

These bracket fungi are far too tough to be edible.

Reference Sources

Mattheck, C., and Weber, K. Manual of Wood Decays in Trees. Arboricultural Association 2003.

Pat O'Reilly, Fascinated by Fungi, 2016.

Dictionary of the Fungi; Paul M. Kirk, Paul F. Cannon, David W. Minter and J. A. Stalpers; CABI, 2008

Taxonomic history and synonym information on these pages is drawn from many sources but in particular from the British Mycological Society's GB Checklist of Fungi and (for basidiomycetes) on Kew's Checklist of the British & Irish Basidiomycota.

Fomes fomentarius - Hoof Fungus on a Poplar in central Scotland

Other web pages about this species

Roger Phillips (UK)

Tom Volk (USA)

Gary Emberger (USA)

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