In order to ascertain the tree genus which the ectomycorhizae are formed on in a mixed stand, it is necessary to either trace the roots to the trunk of a tree or to try a determination of the roots due to their anatomy. A comparison between unequivocally identified roots and the roots in question can help, or keys for determination can be used. Such data are compiled by Cutler et al. (1987): Root Identification Manual of Trees and Shrubs. Chapman and Hall, London, and by Agerer (1987ff): Colour Atlas of Ectomycorrhizae, Einhorn, Schwäbisch Gmünd.