page_title: Inonotus obliquus
section_title: Morphology
hierarchical_section_title: Inonotus obliquus / Morphology
caption_attribution_description: English: development
context_page_description: Inonotus obliquus, commonly known as chaga, 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 sclerotium or mass of mycelium, mostly black because of the presence of massive amounts of melanin. Some people consider chaga to be medicinal.
  I. obliquus is found most commonly in the Circumboreal Region of the Northern Hemisphere, where it is distributed in birch forests.
context_section_description: I. obliquus causes a white heart rot to develop in the host tree. The chaga spores enter the tree through wounds, particularly poorly healed branch stubs. The white rot decay will spread throughout the heartwood of the host. During the infection cycle, penetration of the sapwood occurs only around the sterile exterior mycelium mass. The chaga fungus will continue to cause decay within the living tree for 10–80+ years. While the tree is alive, only sterile mycelial masses are produced (the black exterior conk). The sexual stage begins after the tree, or some portion of the tree, is killed by the infection. I. obliquus will begin to produce fertile fruiting bodies underneath the bark. These bodies begin as a whitish mass that turn to brown with time. Since the sexual stage occurs almost entirely under the bark, the fruiting body is rarely seen. These fruiting bodies produce basidiospores which will spread the infection to other vulnerable trees.
caption: Birch slices showing the development of chaga
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