中文摘要：

黄河上游谷地位于青海省的东部，约处北纬35°20′-36°25′，东经100°55′-102°50′。属青藏高原和黄土高原的过渡地带，海拔1780—4969m，面积约13480km^2，属于大陆性气候或高原大陆性气候类型。本区共有野生种子植物86科、404属、1027种。分别占青海省总科数的95.56％、总属数的79．53％、总种数的44．95％。区系特征如下：（1）种类相对较丰富，木本丰富。（2）植物种的中国特有性高，地区特有性小高。（3）就属的层面而言，中国种子植物区系15个分布区类型，特别是6个热带类型在青海境内唯一于本区都有出现。（4）属和种的分析表明，本区属于以北温带成分，特别是欧亚大陆温、寒地带典型成分为优势的，兼具温性、寒温和高寒类型的温带区系性质。（5）许多种、属和多数热带类型均以本区为边缘分布区，因而区系的边缘性质明显。（6）在植物区系地理方面，本区（特别是孟达林区）为华北区系、横断山区系、青藏高原的高山区系和柴达木高寒荒漠区系的交汇过渡地带，过渡区系性质明显。所以，本区作为远离青藏高原腹地的边缘地带和过渡区系，保持了其高原、高山类型的区系性质，应属距我国北方区系最为接近而高寒区系性质最弱的唐古特地区植物区系。

英文摘要：

The valley in upper reaches of Yellow River is situated in the east of Qinghai, China, between latitude 35°20′- 36° 25′ N and logitude 100°55′- 102°50′ E. This area belongs to the transitional zone of Qinghai-Tibetan Hateau and Loess Hateau at an altitudinal range of 1 780 m to 4 969 m. The total area is c. 13 480 km^2 . Its climate is continental or plateau-continental one. There are 1 027 species of wild seed plants which belong to 86 families and 404 genera in the area. They are 44.95% of the total species, 95.56% of the total families and 79.53% of the total genera in Qinghai, respectively. The floristic characteristics in wild seed plants for the area are as follows： （1） Species and woody ones are richer. （2） Speeies endemic to China also richer, but those endemic to Qinghai are very poor. （3） On the level of genera, all the fifteen distribution types in China, especially all the six tropical ones only occur in the area in Qinghai, （4） On the analysis of genera and species, the flora is temperate in nature which is dominated by North Temperate elements especially the typical elements from the warm and cold zone of Eurasia, and also with some elements of the warm, cold warm and alpine types. （5） The area is of a marginal one in distribution for many species or genera and especially for many tropical ones, so the flora of the area is dear in maginal nature. （6） In floristic geography, it is a converged and transitional region for the Loess Hateau Flora, Hengdnan Mountians Flora, Alpine Qinghai-Tibetan Hateau Flora, as well as Qaidam Alpine Desert Flora, so the flora of the area is also conspiarously a transitional one. Therefore, as a marginal region far from the center of Qingbui-Tibetan Hateau and with a transitional flora more or less keeping the floristic nature of plateau and alpine types, so the valley in upper reaches of Yellow River in Qinghai should he a flora .still belonging to the Tangute one, although it is weaker in alpine nature but conspicuously much more r