Inonotus obliquus

Fruit body is a sterile conk 25–40 cm across; black; deeply cracked, very hard and brittle when dry. Fertile portion is crust-like, thin; dark brown. Tubes are 3–10 mm deep, brittle, usually split in front. Pores are 6–8 per mm, circular; whitish becoming dark brown. Widely effused, no stem. Flesh corky, faintly zoned; bright yellowish brown. Spores are broadly ellipsoid to ovoid, smooth, 9–10 × 5.5–6.5 μm. It is dense, very hard and deeply cracked on the surface resembling something that has been burned. Chaga can be found all year round since it persists on the tree for many years. It has been used as a tonic and tea by the Siberians for hundreds of years. A preparation called Befungin has been used in Russia for cancer treatment since the 1960s. Chaga can be used for dyeing textiles or paper and will yield a yellow or sepia colour depending on what mordant or modifier is used.