Both Grifola frondosa and Meripilus sumsteinei grow at the base of trees and cause a white rot.  Likely weakly parasitic as well as sabropic. The types of wood destroying fungi encountered by pest management professionals and homeowners fall into two basic categories: brown rot and white rot. White rot attacks the cellulose and lignin in the wood giving the wood an off-white appearance. In the later stages the wood becomes spongy to the touch. White rot typically attacks hardwoods and lacks the cubical checking appearance of brown-rotted wood.