Meripilus giganteus

(Pers.) P. Karst.

Mature fruiting bodies at the base of a roadside beech tree in Sittingbourne, Kent.
An emerging mass at the base of horse chestnut at Hampstead Heath, London.
Early-stage development on beech at Hampstead Heath, London.
A mature fruiting mass at the base of a highway red oak in Southend, Essex.
An over-mature fruiting mass at the base of English oak in Laindon, Essex.

Mature fruiting bodies at the base of a roadside beech tree in Sittingbourne, Kent.
An emerging mass at the base of horse chestnut at Hampstead Heath, London.
Early-stage development on beech at Hampstead Heath, London.
A mature fruiting mass at the base of a highway red oak in Southend, Essex.
An over-mature fruiting mass at the base of English oak in Laindon, Essex.
A developing fruit body at the base of beech at Hampstead Heath, UK.
A developing fruit body at the base of beech in Laindon, UK.
A developing fruit body at the base of false acacia in Hockley, UK.
A markedly blackened (bruised) mature fruit body at the base of beech in Kent, UK.
A senescent and well-decayed fruit body at the base of London plane in London, UK.

Common name

Giant polypore.

Often found on

Beech, horse chestnut, sycamore.

Sometimes found on

Hornbeam, maple, oak, plane, whitebeam.

Location

Found fruiting at and around the base of the tree – sometimes emerging from between buttresses and appressed to the butt.

Description

Annual. Soft and fleshy. Develops quickly into a frond-like mass. Begins as a yellowwhite mass. Matures to a tan brown to dark brown upper surface with an off-white pore layer beneath. Fronds bruise black to the touch. White spore. Flesh off-white. In senescence, the fruiting body generally hardens (if exposed) and turns a charcoal black – sometimes with red-brown banding on the fronds. In wet settings, fruiting bodies tend to disintegrate.

Confused with

Grifola frondosa (generally on oak and more grey); Podoscypha multizonata.

Significance

Able to act as a parasite on living trees. Attributed generally to a white rot of the wood but can be attributed also to a soft rot. Can signify locations of root damage following trenching works, construction damage, or other type of disturbance. Decays structural roots and the butt. Attributed to the windthrow of trees. Attributed to crown decline, in some instances – can highlight physiological dysfunction. Trees with targets may need their structural stability tested.