Abstract: The region of Hengduan mountain is a very natural region in floristic nature. Its seed plants' flora is abundant in species, genera and families, complex in geographical elements, strik-ing in endemism and vicariance, and basically temperate in nature. According to the degree of abundance in endemic species and some physiographical features, the region can be floristically divided into three subregions: subregion of NW Yunnan and SW Sichuan, subregion of NW Sichuan to SW Gansu and SE Qinghai, as well as subregion of E to SE Xizang. Based on the ana-lysis of its floristic elements, the region is certainly a knot for clarifying the questions about the relationships between the florogenesis and the plate-tectonics, about the origin of the North temperate flora including that of E Asia, N America and Europe.

Key words: Region of Hengduan moutain

摘要： 横断山脉地区是一个十分自然的植物区系地区，其种子植物区系有丰富的科、属、种，地理成分复杂，特有现象和替代现象明显，基本上是温带植物区系性质。根据特有种丰富的程度以及一些自然地理特征，横断山脉地区在区系上可以划分为3个小区：滇西北川西南小区、川西北甘西南青东南小区和藏东至东南小区。从区系成分分析看，横断山脉地区确实是阐明区系发生与板块运动关系，以及包括东亚、北美、欧洲植物区系在内的北温带植物区系起源的一个关键地区。

关键词: 横断山脉地区, 区系小区, 区系研究, 种子植物区系, 北温带植物区系, 区系发生, 板块运动