The Floristic Study Of Compositae In Loess Plateau

The flora of loess plateau of China belongs to the Holarctic Kingdom in the norhtern China region in the Japan-China Forest Subkingdom in Chinese flora. Compositae is the exclusive family with over 2000 species. The study on the species composition, Taxonomies and characters of family Compositae provide evidence for the research on plant diversity, ecological environmental construction, utilization and protection of plant resources of Loess Plateau, and is significant for the study of origin and differentiation of Compositae .On the basis of several years'botanizing, identification and categorical arrangement of Compositae from Loess Plateau, we worked out the classification system, and statistically analyzed the composition, areal-types and floral characteristics of Compositae, according to FRPS , local plant checklist and many other concerned literatures.The result indicated that, the Compositae in this flora consists of 1 subspecies, 432 species, 120 genera, 10 tribes and 2 subfamilies, with Chrysanthemum, Artemisia Ligularia, Parasenecio,Cirsium,Saussurea, Taraxacum as 7 prominent dominant genera, for which there are 170 species, accounting for 39.35% of the total. The geographic component of Compositae flora in Loess Plateau can be divided into 14 areal types. There are 15 genera in tropic and subtropic, accounting for 12.49% of the total, and the temperate floristic elements(8--15) occupied a dominant proportion including 99 genera, accounting for 82.51% of the total of the genera that are not cosmopolitan. It also dedicates that Compositae in this flora have characteristics of the tropical affinities, diverse composition, many affiliations with near area and ancient origin. With 167 Chinese unique species, accounting for 38.66%, the areal type play an distinctive and important place in the Japan-China Forest Subkingdom .There are 11 species on Loess Plateau accounting 2.55% of the total, with relatively low endemism complicated with various elements.Compared with the Qinling Mountains, Inner Mongolia, Xinjiang and northeast area on the similarity coefficient , Loess Plateau have a higher similarity coefficient with Qinling and Inner Mongolia, all over 50%. Loess Plateau locates at the cross zone of Meng-Xin Desert Area and Qinling humid area.