Abstract: Phenetic analysis was conducted for 32 taxa of Pternopetalum Franchet (Apiaceae ) by using UPGMA algorithm implemented in DELTA packages, based on 60 morphological characters. The results were shown that the 32 taxa were grouped into two distinct phenetic groups, which was represented by P. vulgare and P. tanakae, respectively. The taxonomic structure of two groups and taxa included in each of them are consistent with section division made by previous researches. Six species complexes, P. vulgar, P. davidii, P.botrychioides, P. molle, P. delavayi and P. tanakae complex, were identified on the basis of phenetic relationships and evaluation of morphological variation. Mapping of character state on phenogram revealed that attached position of umbels, morphology of styles, stylopodium and calyx teeth, were possible key characters responsible for earlier morphological divergence in Pternopetalum. Ecological adaptation to heterogeneous habitats in Mt. Hengduan regions was shown to be characteristics of latter species diversification of Pternopetalum, which was evidenced by differentiated habitat and elevation favor, and combined with indistinct morphological divergence in major species complexes.

Key words: Apiaceae