Study On The Taxa Endemic To China In The Angiosperm Flora Of Gansu

Gansu province is located in the transitional zone among Loess Plateau, Qinghai-Xizang Plateau, Innermogolia-Xinjiang Plateau and Qinling Mountains, which reaches from 92°31'to 108°46'E, and from 32°31'to 42°57'N. This region has significant diversity in climate types and complexity in floristic elements. It connects nearby floristic areas extensively.We systematically collected angiosperms, identified and gave an accurate and completely statistics of taxa of angiosperms endemic to China in Gansu region, and revised the divisional scheme used by Lian Yong-shan et al. (1997) on areal-subtype infra areal-types endemic to China. Based on the statistics and divisional scheme of taxa endemic, the basic features, floristic natures and the principal origin of endemic flora of angiosperms to China in Gansu region were discussed. The relationships between areal-style and life-style, the flower color have been analyzed. Also the basic characteristic of the angiosperm flora of Gansu was discussed. The main results and arguments were showed as follows:1. 4 Families and 57 genera endemic to China distribute in Gansu; species endemic to China consisting of 2207 species, 16 subspecies, 177 varieties, 17 forms, and belonging to 581 genera and 144 families. It respectively account of 2% in total families, 5.4% in total genera and 51.7% in total species in Gansu angiosperms.2. The analysis of the taxa endemic to China indicates the temperate nature, transitional character, multicomponent and ancient origin of the angiosperm flora of Gansu. Additionally, it shows Hengduan Mountain elements are chief composition in this region. And it also indicates the contribution of subtropical elements clearly, the impact to the composition of the angiosperm flora of Gansu by Qinghai-Xizang Plateau' apophysis and subtropical relationship of flora origin.3. The distribution figures of genera endemic to China and species contained genera endemic to china reveals abundance centre of Gansu flora.4. The study of the relationship between areal-subtypes and life-style, flower color shows that the diversity of life-style present positively correlation with flower color. The widely distributed light-color flowers in angiosperms flora of Gansu show that Archichlamydeae, Sympetalae and Monocotyledon in angiosperms are homologous. And the connection presents in light-color flowers and primordial of plant evolution. Though the distribution of fuscous-color flowers are relative localization, the proportion of fuscous color in Sympetalae and high altitude areal-subtype (15-5, 15-8) is higher, it indicates Himalayas apophysis certainly affect the angiosperms flora of Gansu.The flora of taxa endemic to China of Gansu province was completely researched at the three taxonomic levels—families, genera and especially species endemic to China of this region. All results make us knowing comprehensively composition, nature, character and origin of the angiosperms flora of Gansu. Also the relations between areal-subtype and life-style, flower color were profitably explored.