Inonotus obliquus

''Inonotus obliquus'', commonly called chaga , is a fungus in the family Hymenochaetaceae. It is parasitic on birch and other trees. The sterile conk is irregularly formed and resembles burnt charcoal. It is not the fruiting body of the fungus, but a sclerotium or mass of mycelium, mostly black because of a great amount of melanin. Some people consider chaga medicinal.

''Inonotus obliquus'' is found most commonly in the Circumboreal Region of the Northern Hemisphere, where it is distributed in birch forests.