Perenniporia fraxinea

(Bull.) Ryvarden

Mature brackets adorning the base of a mature ash in Bishop’s Stortford, Hertfordshire.
Numerous brackets growing without a pore surface on soil on a veteran ash in Hertford, Hertfordshire
Massive brackets beneath lapsed pollard heads on a veteran beech at Epping Forest, Essex
A developing tier of brackets at the base of a beech at Hatfield Forest, Essex
The beige flesh and brown tube layer (plus white spore) distinguish this fungus from other species

Mature brackets adorning the base of a mature ash in Bishop’s Stortford, Hertfordshire.
Numerous brackets growing without a pore surface on soil on a veteran ash in Hertford, Hertfordshire
Massive brackets beneath lapsed pollard heads on a veteran beech at Epping Forest, Essex
A developing tier of brackets at the base of a beech at Hatfield Forest, Essex
The beige flesh and brown tube layer (plus white spore) distinguish this fungus from other species
An aberrant (potentially P. robiniophila) fruit body on false acacia in Laindon, UK.
Senescent fruit body at the main stem union on false acacia in Ware, UK.
A developing fruit body at the base of ash in Rochford, UK.
Very large bracket at the base of ash in London, UK.
Fresh yellow growth on a mature bracket on ash at Hampstead Heath, UK.

Common name

Giant ash bracket.

Often found on

Ash, beech, false acacia.

Sometimes found on

Hornbeam, horse chestnut, oak, plane, poplar, sycamore.

Location

Found at the base of the tree and on surface roots. Rarely up the stem to 2-3m.

Description

Perennial. Tough and woody. Can become very large (and heavy). Found singularly or abundantly. Begins as a beige-white mass. Bracket forms to a beige-brown to green (or brown-purple) upper surface (sometimes algal-stained), often rimmed beige-white to yellow, and with a white pore layer beneath. Ends of such brackets may bend slightly under pressure. Spore abundant and white. Flesh beige. Can exude a milky liquid when cut. Tube layer darker brown. Senescent brackets darken and become a dark brown-green and often remain attached to the tree.

Confused with

Ganoderma australe (brown flesh); Rigidoporus ulmarius (white flesh and shallow cinnamon orange tube layer).

Significance

Attributed to a simultaneous white rot of the wood – can cause the wood to shear at the roots and butt. High-profile cases have made this fungus much maligned. Considered pathogenic though also able to act saprotrophically. Where targets exist, investigations into stem hollowness and stability may be required. Larger brackets indicate potentially long-standing decay.