橐吾属的起源、演化与地理分布

THE ORIGIN,EVOLUTION AND DISTRIBUTION OF LIGULARIA CASS.(COMPOSITAE)

橐吾属Ligularia Cass.是菊科千里光族款冬亚族的一个大属。在款冬亚族中本属与大吾风草属Farfugium Lindl.亲缘关系最近,但进化程度较高。本属包括6组、11系129种。所有种类均分布在亚洲,仅2种扩散至欧洲。在东亚地区有119种,占该属总种数的96％。高度集中在横断山区的有4组、6系67种,其中61种为特有种,占该属总组数的66％,总系数的54.5％,总种数的52％。这个事实表明了横断山区是该属的多度中心和多样化中心。通过性状分析,伞房组伞房系Sect.Corymbosae,Ser.Calthifoliae叶肾形,具掌状叶脉,头状花序大而少,排列呈伞房状,总苞半球形,被认为是该属的原始类群。原始种齿叶橐吾L.dentata和鹿蹄橐吾L.hodgsonii的分布区从我国四川东部经过湖北、湖南、安徽、福建等省至日本。这个分布格局与近缘属大吴风草属Farfugium一致。 根据共同起源原理,这两个属的祖先极有可能就发生在这一地区。因此我们推测东亚地区从中国四川东部至日本这一地区是本属的发源地,然而根据地质历史和现代分布,作者认为中国中部(包括四川东部)是本属的初始起源地。该属起源后,基本上沿亚洲南缘的山地扩散,少数种类向东北至亚洲东北部。本属起源时间至少不晚于中白垩纪。

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.