Polypore fungi like Inonotus Obliquus (chaga) are a unique type of fungi unlike fleshy mushrooms, most of these fungi can be found even during dry weather or in the winter. Polypores can be easily distinguished from the other fungi by their typically hard exterior, usual "non-mushroom" shape and they usually grow on wood acting as wood de-composers.
Polypore fungi decompose wood, recycling the nutrients and minerals in the wood and releasing them over a long period of time often several hundred years from a single large downed tree. Many species can also act as a pathogen to living trees like Laetiporus sulphureus, the sulfur shelf or chicken of the woods, Grifola frondosa, hen of the woods, sheepshead or maitake.
Several polypores are used in oriental herbal medicine as tea-like extracts, including Ganoderma lucidum (reishi mushroom), Polyporus umbellatus, and Grifola frondosa (maitake) and Inonotus Obliquus (chaga). The polypores wood-degrading and especially lignin-degrading ability are how they can aid in the availability of nutrition to other insects, animals and even humans.
As a wood decaying fungi polypores can utilize two different ways in which to rot or breakdown their host tree. Wood is composed mostly of cellulose (white) and lignin (brown). Cellulose makes up the primary wall of all plant cells. Many plants have a secondary wall of lignin inside the primary one, especially in wood. Brown rot fungi degrade the white cellulose leaving the brown lignin behind. White rot fungi degrade the lignin and leave the white cellulose behind. Brown rot fungi degrade the primary walls and leaving the secondary lignin behind. Thus brown rotted wood crumbles to dust since there is no primary wall structure. White rot fungi leave the cellulose of the primary walls behind. Inonotus Obliquus (chaga), is a white rot fungi. The lignin-degrading enzymes of white rot fungi will also degrade toxic wastes that have the same general chemical configuration, such as PCB's and PCP's. Chaga is generally known as non-toxic fungi because of this fact.