Phylogenetic relationships of Salix (Salicaceae) based on rbcL sequence data

Nucleotide sequences of the chloroplast-encoded rbcL gene were used to exam ine phylogenetic relationships of the genus Salix together with other allie d genera of the family Salicaceae. Phylogenetic analyses of rbcL, sequences strongly suggest the monophyly of three commonly recognized genera (Chosen ia, Salix, and Toisusu). Two monophyletic groups are recognized within the larger monophyletic group. They do not correspond with any infrageneric tax a proposed so far. With regard to character evolution, it is thought that t he reduction of stamen number from more than two stamens to two might occur in at least three lineages and that fused bud scales evolved several times and/or the reverse evolution occurred from fused to free. Some types of po llen surfaces are considered to have evolved independently.