Inonotus obliquus, commonly known as
chaga mushroom (a
Latinisation of the Russian term
'чага'), is a
fungus in the family
Hymenochaetaceae. It is
parasitic on
birch and other trees. The sterile conk is irregularly formed and has the appearance of burnt charcoal. It is not the
fruiting body of the fungus, but a
sclerotia or mass of
mycelium, mostly black due to the presence of massive amounts of
melanin. The fertile fruiting body can be found very rarely as a resupinate (crustose) fungus on or near the clinker, usually appearing after the host tree is dead.
I. obliquus grows in birch forests of Russia, Korea, Eastern and Northern Europe, northern areas of the United States, in the
North Carolina mountains and in Canada.