关键词: 雅鲁藏布江中游沙地, 阿拉善荒漠, 植物区系

Abstract: The floras of the sandy land in the Middle Yarlung Zangbo Basin and the Alxa Desert were compared.From the floristic components it can be seen that the flora of the sandy land in the Middle Yarlung Zangbo Basin is predominated by Eastasian elements,and the flora of the Alxa Desert by the central desert elements of Asia.Moreover,the superiority of the endemic species in the two floras are quite clear.But the most endemic species in the flora of this sandy land have been differentiated in the high altitude,cold and drought habitat during the lift of the Qinghai-Xizang Plateau,and the endemic species in the flora of the Alxa Desert are mostly the relict ones.The floras both in the sandy land and in Alxa Desert are all with palaeo tropical origins,but the former is an new and young one formed in the Period of the Plateau rising based on the Tertiary tropical flora,and the latter retains the ancient features of the tropical origin,especially the Mediterranean sea origin.

Key words: The sandy land in the Middle Yarlung Zangbo Basin, The Alxa Desert, Flora