Molecular analysis has shown it is closely related to X. subtomentosus, and it was probably previously overlooked due to its similar appearance. It has a strong preference in associating with Populus species whereas X. chrysonemus associates with Quercus, X. subtomentosus with broadleaved hosts and X. ferrugineus with conifers. Microscopically, the spores of X. silwoodensis resemble those of X. chrysonemus, but are different from both X. subtomentosus and X. ferrugineus.