Tinder fungus is a polypore living on deciduous trees. It has a hoof-like hard perennial fruit body. Its upper surface looks zone-like and is gray or brownish in colour. The lower surface pore layer is dirty white or purple. The spores are released when the outer shell is damaged and attach themselves to host trees.

It grows most commonly on birch (Betula sp.) and alders (Alnus sp.), but also on other deciduous trees. It covers the circumpolar regions in both the Northern and Southern Hemispheres.

True to its name, the tinder fungus has been used for thousands of years as kindling for fire. In folk medicine, it has also been used to treat various pains, such as earaches and as a herbal remedy for its antibiotic effects.

Tinder fungus is a decaying fungus which lives on dead trees laying on the ground and living trees. It forms white rot and decays wood quite quickly. Polypores like Gloeoporus pannocinctus and Antrodiella semisupina grow in trees decayed by tinder fungi. The tinder fungus is a common species and benefits from forest management treatments that support deciduous trees and increase deadwood.