A revision of Clematis sect. Meclatis (Ranunculaceae)
铁线莲属黄花铁线莲组修订

Clematis sect. Meclatis is revised in this paper. Brief taxonomic history and geographical distribution of the section are given, its systematic position and the relationships among the species are discussed, and the evolutionary trends of some characters in the section are evaluated. Clematis akebioides (Maxim.) Veitch and C. tangutica (Maxim.) Korsh. are considered the primitive species in the section, whereas C. caudigera W. T. Wang and C. corniculata W. T. Wang are considered the advanced ones. The western edge of the Qinghai-Xizang (Tibet) plateau with the Pamirs and the adjacent mountains, the highest land mass in the world, where 10 species of the section are concentrated, is regarded as the distribution center, and the eastern edge of the Qinghai-Xizang (Tibet) plateau, where the two primitive species, C. akebioides and C. tangutica, sympatrically occur, may be the center of origin of the section. The inclusion of C. ispahanica Boiss. and C. graveolens Lindl. in sect. Meclatis by some authors is not accepted, with the former being a member of sect. Clematis, and the latter a member of sect. Brachiatae Snoeijer. A new variety, C. intricata Bunge var. intrapuberula W. T. Wang, is described, and two new combinations, C. tangutica var. mongolica (Grey-Wilson) W. T. Wang and C. tibetana Kuntze var. pamiralaica (Grey-Wilson) W. T. Wang, is proposed. As a result, 13 species and 13 varieties are recognized in sect. Meclatis. They are keyed, described, and illustrated.