Quercus petraea (Matt.) Liebl. and Q. pubescens Willd. are two closely related taxa. No specific single marker, either morphological or molecular, has been identified to distinguish the two species until now. In the present study morphoanatomical and molecular traits (simple sequence repeatsa SSR loci) were investigated in an attempt to characterize and to discriminate between these two oak species. At the morphological level, the applied statistics (nested ANOVA and discriminant analysis) suggest that the micromorphological features are the most eAective for this purpose. The wide range of macromorphological variation observed can confound the classification of many individuals into either Q. petraea and Q. pubescens. Analysis of microsatellite data indicates that most of the genetic variation is contained within, rather than between, species. The lack of molecular divergence could be attributed to either relatively rapid and recent diAerentiation or to extensive hybridization following secondary contact of the taxa. # 2000 Annals of Botany Company