Recent phylogenetic analyses revealed a grade with Ranunculales,Sabiales,Proteales,Trochodendrales,and Buxales as first branching eudicots,with the respective positions of Proteales and Sabiales still lacking statistical confidence.As previous analyses of conserved plastid genes remain inconclusive,we aimed to use and evaluate a representative set of plastid introns (group Ⅰ:trnL; group Ⅱ:petD,rpll6,trnK) and intergenic spacers (trnL-F,petB-petD,atpB-rbcL,rps3-rpll6) in comparison to the rapidly evolving matK and slowly evolving atpB and rbcL genes.Overall patterns of microstructural mutations converged across genomic regions,underscoring the existence of a general mutational pattern throughout the plastid genome.Phylogenetic signal differed strongly between functionally and structurally different genomic regions and was highest in matK,followed by spacers,then group Ⅱ and group Ⅰ introns.The more conserved atpB and rbcL coding regions showed distinctly lower phylogenetic information content.Parsimony,maximum likelihood,and Bayesian phylogenetic analyses based on the combined dataset of non-coding and rapidly evolving regions (＞14 000 aligned characters) converged to a backbone topology ofeudicots with Ranunculales branching first,a Proteales-Sabiales clade second,followed by Trochodendrales and Buxales.Gunnerales generally appeared as sister to all remaining core eudicots with maximum support.Our results show that a small number of intron and spacer sequences allow similar insights into phylogenetic relationships of eudicots compared to datasets of many combined genes.The non-coding proportion of the plastid genome thus can be considered an important information source for plastid phylogenomics.