Heterobasidion parviporum 

Heterobasidion parviporum is a common polypore that lives on spruce (Picea abies). It has perennial fruit body, which could come with or without a cap. While its upper surface is brown, it is otherwise cream coloured. The species spreads through the root system of one tree to another; and when spores fly, for example, to the surface of a coniferous tree stump.

Heterobasidion parviporum grows on tree roots or fallen trunks. Its range extends from Central and Northern Europe to South Siberia to China and Japan.

Heterobasidion parviporum can be confused with its relative Heterobasidion annosum. The species decays the tree upwards from its root system.

Heterobasidion parviporum is an effective wood decayer that causes white rot on its roots and base. It thrives in many sites, especially in commercial forests. It can be combated biologically by spraying solution containing gray orchid fungus spores on fresh stumps.