Fomitopsis betulina

(Bull.) B.K. Cui, M.L. Han & Y.C. Dai

A mature fruiting body on a fallen silver birch at Hampstead Heath, London.
A young fruiting body emerging from a lenticel band on a dead silver birch in Billericay, Essex
Abundant along a fallen silver birch stem in Epping Forest, Essex
A mature bracket 10-12m up a living silver birch in Hockley Woods, Essex
Mature brackets with brown upper surfaces on a fallen birch at Thorndon Country Park, Essex

A mature fruiting body on a fallen silver birch at Hampstead Heath, London.
A young fruiting body emerging from a lenticel band on a dead silver birch in Billericay, Essex
Abundant along a fallen silver birch stem in Epping Forest, Essex
A mature bracket 10-12m up a living silver birch in Hockley Woods, Essex
Mature brackets with brown upper surfaces on a fallen birch at Thorndon Country Park, Essex
Young emerging fruit bodies on birch in Hockley, UK.
Cleaving through lenticel banding on birch in Rochford, UK.
Over-mature fruit body with a distinct separation between upper surface and tube layer on birch in the New Forest, UK.
Large and mature brackets on birch in the New Forest, UK.
Developing tier of brackets on a birch stem at Hampstead Heath, UK.

Common name

Birch polypore, Razorstrop bracket.

Often found on

Silver birch.

Sometimes found on

Other birch species.

Location

Found growing at locations along the entire above-ground scaffold structure of the host tree. Abundant on dead trees, most notably.

Description

Annual . Rubbery. Emerges from lenticel bands as an off-white mass. Mature fruiting bodies have a greyish-white to tan-brown upper surface and off-white pore surface that can tinge golden brown in post-maturity. Flesh white. Shallow tube layer 1-2mm deep. Desiccates to a mottled medium to dark grey – sometimes greenish.

Confused with

Daedaleopsis confragosa (often growing on birch in similar locations – this fungus has maze-like pores and often blushed reddish brown).

Significance

Attributed to a cubical brown rot of the wood. Parasitic – at least, mildly. Exists as a vascular endophyte, prior to colonisation. Colonises when host tree becomes stressed. Presence therefore signals physiological stress and decline. Where targets exist, tree removal may be justifiable.