THE ORIGIN,EVOLUTION AND DISTRIBUTION OF LIGULARIA CASS.(COMPOSITAE)
橐吾属的起源,演化与地理分布

The genus Ligularia Cass. is one of the large genera in Compositae-Senecioneae-Tussilagininae. In subtrib. Tussilaginae, Ligularia is closely related to, but more advanced than, the genus Farfugium Lindl. It includes six sections, 11 series and 129 species. All the taxa are distributed in Asia with only two species extending to Europe. There are 119 species in E. Asia, Comprising 96% of the world total. The highest concentration of species in E. Asia occurs in the Hengduan Mountains. In this area there are four section, six series and 67 species, of which 61 species are local endemics; thus 66% of sections, 54. 5% of series and about 52% of species in the world occur in this small area, indicating that it is a major distribution centre for Ligularia. According to character analysis, sect. Corymbosae ser. Calthifo-liae with 5 species was considered as the most primitive group in this genus, which has reni-form leaves, palmate veins, a few large capitula (arranging in Corymb-like inflorescence), and semispherical involucre etc. The primitive species, L. dentata and L. hodgsonii, are distributed from E. Sichuan to Japan via Hubei, Hunnan, Anhui, Fujian. This distribution pattern is consistent with that of its allied genus, Farfugium. According to the principle of common origin, the ancestors of the two genera appeared most probably in the same area. It was inferred that the area from E. Sichuan of China to Japan was the original area of the genus Ligularia, However, on the basis of geological history and the modern distribution of this genus, the author considers that central China with E. Sichuan might be the primary o-riginal area of Ligularia. Its dispersal route was mainly along the mountains of southern margin of Asia, with relatively few members dispersed northea stwards to NE. Asia. The original time of the genus Ligularia was at least not later than the middle Cretaceous.