phellinus tremulae, a parasitic polypore fungus, growing on the trunk of a dead, fallen aspen tree, populus tremula.

aspen background bark biology botanical botany brown damage dead decay deciduous disease ecology environment fallen forest fruiting fungi fungus grow growing growth heart heartrot host hymenochaetaceae infected infection mushroom mycology natural nature obligate parasite parasitic polypore populus poroid rot rotting species tree trembling tremula trunk vegetation wild wood woodland