Phylogenetic relationships of Salix L. subg. Salix species (Salicaceae) according to sequencing data of intergenic spacers of the chloroplast genome and ITS rDNA

A phylogenetic analysis based on a comparison of nucleotide sequences of six regions (petN-psbM, trnD-trnT, trnC-petN, psaA-ycf3, petG-trnP, and rpoB-trnC) of cpDNA and ITS rDNA allowed for elucidating the relationship among species and sections belonging to the Salix subgenus and, more generally, to the Salix genus, as well as revealing the relations of the Chosenia genus. The definition of the subgenera Pleuradenia (including the Urbanianae section and the Chosenia genus), Salix (without the Triandrae section), Triandrae, and Longifoliae is essentially consistent with current classification schemes of the Salix genus. The previously defined genera of Chosenia and Toisusu (Urbanianae) are not only merged with the Salix genus but are also closely related between themselves. The Protitea subgenus only corresponds to the American species of the Humboldtianae section (S. humboldtiana, S. amygdaloides, S. gooddingii). The relationship of S. chaenomeloides, which is a nomenclatural type of this subgenus, as well as the relationship of the Wilsonia section, remains unresolved. The Humboldtianae section should be interpreted more narrowly, apparently, separating Acmophyllae and Tetraspermae sections from it. The monotypic American Floridanae section is related to the Salix, Salicaster, Tetraspermae, and Wilsonia sections.