Wood traits in parental and hybrid species of Sorbus

The genus Sorbus is an example of taxonomic complexity arising from the combined effects of hybridization, polyploidy, and apomixis. In this study, a comparison of the diagnostic microscopic characteristics of wood, together with the quantitative traits of vascular anatomy, fiber morphology, and cell wall constituents in parental (Sorbus aria, Sorbus aucuparia, Sorbets chamaemespilus) and hybrid (Sorbus haljamovae, Sorbus montisalpae, Sorbus zuzanae) taxa, was undertaken to discriminate each one of the examined taxa from the other and also to examine relatedness among parental and hybrid taxa. Chemical profiles of the degree of polymerization of cellulose were found to be the discriminating chemotaxonomic marker for all taxa. Sorbus haljamovae was determined to be the only taxon distinctively identified microscopically and distinguishable from the other examined taxa. The use of cell wall constituent traits provided a better segregation of hybrid taxa from their putative parental species than did the application of vascular anatomy variables. Sorbus zuzanae and Sorbus haljamovae formed isolated clusters that were distinctively segregated from all the other examined taxa. The results of this study indicate that the majority of wood traits in Sorbus hybrids do not exhibit an intermediate position between the parental taxa.