The Systematic Classification And Floristic Geography Of Saussurea In Gansu Province

The systematic classification and floristic geography of Saussurea in Gansu Province were studied in this thesis. The all species of the family Saussurea were tried to recognize in Gansu province based on herbarium examinations of more than one thousand one hundred specimens from three herbaria(abbreviated as PE, QTPMB,WUK,NWTC), literatures and additional filed work, they had also contributed to reveal the main morphological characters and their evolution studies. Based on the materials of systematic classification and geographic distribution, the modern geographic distribution patterns(distribution types) of all species and genera in this region were classified and taken into statistical analysis. And used similarity coefficient analysis to compare with adjacent regions to display the geographical distribution features, floristic elements, the relationship between floristic similarity and the floristic origin of the family Saussurea in Gansu. The results were su mmarized as follows:1.70 genera(include 4 subjen) of the family Saussurea were recognized in Gansn province;Morphological description, localities, habitats and specimens cite were given in detail and systematic key to the genera and species had been made.2. S.quercifolia W. W. Smith., S.pseudomalitiosa Lipschitz., S. polycephala Handel-Mazzetii., S.sobarocephala Diels., S.acrophila Diels., S.dielsiana Koidzumi were recognized as new records species distributed in Gansu province.3. The areal-types of genera of Saussurea could be divided into 5 types and 2 subtypes. The florastic characteristics of Saussurea in Gansu was temperature zone based on Chinese Himalaya.4. It was abundance in species and diversity in forms of the family Saussurea in Gansu, accounted for 24% of the total, among them the temperate distributed elements of Saussurea were 49 species,accounted for 70% of Saussurea in Gansu and absolutely dominant. The endemic to China species were obvious.5. According to different areal divisions,the geographic distribution ranges of the family in Gansu were divided into 2 regions: one is alpine plateau of the east edge of Qingzang plateau, the other is Qilian mountain of the north edge of Qingzang plateau, this two regions were seemed to be the centre of the distribution density and the species diversity of Saussurea in Gansu province.6. There were higher floristic similarity of genera and species between Qinghai and Sichuan, but the similarity coefficient between Xinjiang, Ningxia,Yunnan,Inner Mongolia, as well as Xizang was lower; all of above indicated that the western the Hengduan Mountains and East Himalaya of china was the distribution center of Saussurea.7. The Saussurea in Gansu province was closely linked with Hengduan Mountain Region and Himalaya, it is the important fringe of the northern extension of Hengduan Mountain Region.