Abstract: Tree peony, being crowned the title “King of Flowers” in China, is of great medicinal, ornamental, and economic values. In the present study, the phylogeny of the wild tree peony species (section Moutan, Paeonia, Paeoniaceae), represented by twelve accessions collected from all eight species in the section, was investigated based on the DNA sequence in five DNA fragments from both nuclear (Adh1A, Adh2 and GPAT) and chloroplast (trnS-trnG and rps16-trnQ) genomes, as well as morphological characters. Both maximum parsimony (MP) and Bayesian inference of phylogeny (BI) trees were reconstructed based on the combined data of the DNA sequences and morphological data, respectively. The MP and BI trees have the similar topology, and the sect. Moutan clearly branched into two clades. One clade consists of two species, P. delavayi and P. ludlowii, corresponding to the subsect. Delavayanae, and another clade is composed of other six species. Within the second clade, the six species can be divided into three subclades consisting of P. rockii and P. decomposita, P. jishanensis and P. qiui, P. suffruticosa and P. ostii, respectively. Among the three subclades, P. jishanensis/P. qiui is most closely related to P. suffruticosa/P. ostii. These results provide up to date the clearest picture of the phylogeny of wild tree peony species in the sect. Moutan.

Key words: chloroplast DNA, morphological character, nuclear DNA, Paeonia sect. Moutan, phylogeny