Study on the genera endemic to China in the angiosperm flora of Gansu

Gansu Province is located in the transitional zone among Loess Plateau, QinghaiTibet Plateau, InnermogoliaXinjiang Plateau and Qinling Mountains. This region has significant diversity in climate types and complexity in floristic elements. Genera endemic to China in the angiosperm flora of Gansu Province accounted to 57 genera, consisting of 72 species, 1 subspecies, 6 varieties and belonging to 38 families. The quantity is superior to ones of other provinces or autonomous regions of the yellow river. In this paper, the divisional scheme used by Lian Yongshan et al. (1997) on arealsubtype infra arealtypes endemic to China was revised. The numbers of genera and the composition of genera type in every arealsubtype on the genera endemic to China in the angiosperm flora of Gansu Province were studied. The results showed that the subtropical species were the dominant, including 24 genera, 42.1% of total genera; Central China species and Hengduanshan Mountains species situated in the first and second for the quantity of genera separately, 15 genera and 13 genera, 26.3% and 22.8% of total genera; the genera with one species, including monotypic genera and oligotypic to moretypic genera only one species distributed in Gansu, were the most important genera type, 47 genera, 82.5 % of total genera. Wen County is undoubtedly the abundance centre of endemism in the Angiosperm Flora of Gansu.