A phylogenetic analysis of hydrangeaceae based on sequences of the plastid gene matk and their combination with rbcl and morphological data

DNA sequences of the plastid gene matK were used alone and in combination with rbcL and morphological data in analyses of phylogenetic relationships in Hydrangeaceae. A suggested relationship of Hydrostachys to Hydrangeaceae was examined, but the maximum parsimony analyses of the matK data and the data set that combines matK and rbcL place Hydrostachys outside of Hydrangeaceae. The DNA sequence data sets both alone and in combination produced congruent results. A Jamesia + Fendlera clade ( subfamily Jamesioideae) was the sister of the rest of the family ( subfamily Hydrangeoideae). Two tribes, Philadelpheae and Hydrangeeae, are recognized in Hydrangeoideae. Philadelpheae included three primary clades: (1) Philadelphus + Carpenteria, (2) Deutzia + Kirengeshoma, and (3) Fendlerella + Whipplea. Relationships in Hydrangeeae remain poorly resolved. A Cardiandra + Deinanthe clade was placed robustly as the sister of the rest of the Hydrangeeae only in analyses in which matK sequences were combined with other data. Broussaisia, Decumaria, Dichroa, Pileostegia, Platycrater, and Schizophragma were nested among species of Hydrangea. Relationships in this Hydrangea clade (the most inclusive monophyletic group that included species of Hydrangea) were poorly resolved, except for the monophyly of (1) Decumaria, Pileostegia, and Schizophragma; (2) Broussaisia, Dichroa, Hydrangea hirta, and Hydrangea macrophylla; (3) Platycrater, Hydrangea involucrata, and Hydrangea aspera; and (4) Hydrangea anomala and Hydrangea section Cornidia. Conflict between the morphological and matK data weaken support for the monophyly of both Philadelpheae and the Hydrangea clade; however, the addition of the morphological data strengthens support for Hydrangeoideae, Hydrangeeae, and the sister group relationship of the Hydrangea clade and Cardiandra + Deinanthe.