XVI International Botanical Congess

The tribe Neillieae, characterized within the Rosaceae by stipulate simple leaves, dehiscent follicles, and ovoid seeds, comprises two eastern Asian genera Neillia and Stephanandra, and the eastern Asia-North America intercontinental disjunct genus Physocarpus. To elucidate the phylogenetic relationships of the tribe Neillieae, sequences of the internal transcribed spacer (ITS) region of nrDNA sequences were determined for 27 taxa, representing 18 of ca. 25 species of the tribe and six outgroups. The maximum parsimony analysis shows that the tribe Neillieae is a well supported monophyletic group and that two major clades (Physocarpus and Neillia-Stephanandra) are found within the tribe. The results reveal that Stephanandra is paraphyletic and the eastern Asian P. amurensis is nested among North American species of Physocarpus. These findings suggest that members of Neillia and Stephanandra should be regarded as congeneric and at least two biogeographic events occur between eastern Asia and North America in the tribe Neillieae.