Chaga

Chaga, Inonotus obliquus, is a fungus in the family Hymenochaetaceae that parasitises birch and other trees, causing white heart rot that can develop in a host tree over ten to eighty or more years. Rather than a conventional fruiting body it forms a sterile conk, or sclerotium, a hardened mass of mycelium rich in melanin that resembles burnt charcoal, with a visible mycelial canker roughly ten to twenty five centimetres wide and an underlying crust reaching five to fifty centimetres long. It is found most often in circumboreal regions of the Northern Hemisphere, particularly in birch forests, though it also grows on alder, beech and poplar trees. Chaga contains extremely high concentrations of oxalates, and while the Potawatomi people traditionally used it as tinder for fire keeping, it is marketed today as a dietary supplement despite lacking sufficient scientific evidence for its safety or effectiveness, and its oxalate content means chronic consumption can pose a risk of kidney complications.