Phylogenetic relationships of the Hamamelidaceae inferred from sequences of internal transcribed spacers (ITS) of nuclear ribosomal DNA.

Intergeneric relationships in the Hamamelidaceae have long been controversial. In this study, sequences of the internal transcribed spacers of nuclear ribosomal DNA were used to reconstruct the phylogeny for the Hamamelidaceae. Three major clades were recognized in the ITS-based phylogenetic tree: (1) Mytilaria-Exbucklandia-Rhodoleia, (2) Disanthus, and (3) the Hamamelidoideae. Within the Hamamelidoideae there were three well-supported lineages: (1) Corylopsis-Loropetalum-Tetrathyrium-Maingaya-Matudaea, (2) Eustigmateae sensu Endress, plus Molinadendron-Dicoryphinae, and (3) Hamamelis-Fothergilleae sensu Endress, excluding Matudaea and Molinadendron. The Exbucklandioideae sensu Endress were not monophyletic, nor were the tribes in the Hamamelidoideae in their current circumscriptions except for the Corylopsideae. Strap-shaped petals, apetaly, and wind pollination have evolved three times independently in the Hamamelidaceae s.s. (Hamamelidaceae minus Altingioideae), suggesting that homoplasy should be considered in future classifications of the family.