Molecular phylogeny of Salix L. (Salicaceae) inferred from three chloroplast datasets and its systematic implications

Abstract

AbstractSalix is a taxonomically difficult genus and its generic limits and infrageneric division are still highly controversial. We employed sequences of the chloroplast rbcL gene, trnD‐T spacer and atpB‐rbcL spacer for phylogenetic analyses of Salix. The results strongly support that Salix, Toisusu and Chosenia form a monophyletic group, confirming the merge of Toisusu and Chosenia with Salix. Within Salix s.l., two major clades are recognizable; one contains species of subgenus Salix (excluding sections Triandrae and Urbanianae), with the New World and the Old World species forming strongly supported clades, respectively; and the other includes sections Triandrae, Urbanianae, Chosenia and all species of subgenera Chamaetia and Vetrix, with the latter two subgenera forming a robustly supported subclade but with low resolution. A new infrageneric classification of Salix is herein proposed. The previously recognized subgenus Salix is split into three subgenera: Salix, Chosenia and Triandrae, and subgenera Chamaetia and Vetrix are combined as subgenus Vetrix.