Extract from Dr. Sang's dissertation:
Subsections of Section Paeonia
Previous cytogenetic data (Stebbins, 1938b; Tzanoudakis, 1977, 1983) and new molecular phylogenetic data (Sang et al., in press, in prep.; Sang, in prep.) suggest modifications in the classification of section Paeonia. Three subsections may be designed to accommodate morphological and molecular phylogenetic information.
1. One subsection would include Asian species with dissected leaves that were derived through strict divergent evolution and the hybrid species derived among them (i.e., P. anomala, P. veitchii, P. lactiflora. P. emodi, P. sterniana, and P. xinjiangensis) .
2. The second subsection would contain eastern Asian species with fewer and broader leaflets belonging to the smaller ITS clade (i.e., P.mairei. P. obovata. and P. japonica).
3. The third subsection would include all the Mediterranean species that may have been derived through hybridization between the first two subsections. This subsection would accommodate a wide range of morphological variation (see later discussion), and thus may be subject to further subdivision for a maximally predictive classification.
Paeonia tenuifolia with extremely dissected leaves, does not appear to fall clearly in this subsection. Further investigations are needed to clarify the maternal parent of this species, which was assumed to be an extinct lineage (Fig. 6) . Likewise, more detailed molecular phylogenetic studies should be done to verify possible hybrid origins for P. arietina P. humilis, P. officinalis, and P. parnassica.
Final decisions on major changes in the current classification of section Paeonia, therefore, might be held until these studies are completed and correlated with ongoing taxonomic revisionary studies by D. Hong (Institute of Botany, Beijing; pers. comm.) and N. Rowland (University of Reading, London; pers. comm.).