Mushrooms have a very special place in a forest ecology. The medicinal mushrooms we collect live on trees which they help to break down. In the process of decomposing the tree fiber, these mushrooms absorb many of the trace minerals and other nutrients held in the host tree. The Reishi and Turkey Tails are known as polypores, while the shitake is a gilled mushroom and the Chaga is a sterile conk.
Mushrooms have a long history of use as food and medicine throughout the world, and are currently being investigated for use in many health concerns we are faced with in this present time. You can find more information in the book, Medicinal Mushrooms by Christopher Hobbs.