Abstract: Much of the recent progress in understanding angiosperm phylogeny has been achieved using multigene or plastid genome datasets. However, the size of a dataset required to achieve sufficient resolution is largely unclear. The ycf2 gene is the largest plastid gene in angiosperms and it was used as part of multigene datasets in several earlier investigations on angiosperm relationships. In this study, we show that the ycf2 gene alone can provide a generally well-supported phylogeny that is consistent with those inferred from the most comprehensive multigene or plastid genome datasets. The phylogenetic signal of the ycf2 gene is likely derived from the combination of its long sequence length and low rate of nucleotide substitution. The ycf2 gene may provide a low-cost alternative to comprehensive multigene or genome datasets for investigating angiosperm relationships.

Key words: angiosperm phylogeny, indel, multigene dataset, molecular evolution.