 Hydnellum peckii is a mycorrhizal fungus , and as such establishes a mutualistic relationship with the roots of certain trees ( referred to as " hosts " ) , in which the fungus exchanges minerals and amino acids extracted from the soil for fixed carbon from the host . The subterranean hyphae of the fungus grow a sheath of tissue around the rootlets of a broad range of tree species , in an intimate association that is especially beneficial to the host ( termed ectomycorrhizal ) , as the fungus produces enzymes that <unk> organic compounds and facilitate the transfer of nutrients to the tree . 
