Fu ling (Reishi Mushroom) comes from the Poria cocos fungus, found in the Polyporaceae family. Fu ling is used as a general purpose yin tonic, promoting health and balance in the body. It also appears to promote urination and generally healthy blood flow, and some herbalists also prescribe it as a sedative, since the yin effects are calming. Fu ling acts specifically on the heart, spleen, and kidney meridians, and it is used to treat a variety of conditions which are believed to be associated with these meridians.