中国黄耆属植物旱生类群的区系特点和生态地理分布

根据种的现代地理分布、分布区类型、地理宗的替代关系和生态２特点对中国黄耆属植物的旱生类群进行了研究。结果表明，国产该类群植物９３种，可划分为８个分布区类型和１４个亚型。依其生态理分布规律，又可将这些类群划分为４个生态系列或称为生态区，即帕米尔－昆仑－羌唐生态区，天山－阿尔泰生态区、伊犁－塔城谷地生态区和蒙新荒漠东部生态区。分析认为：黄耆属植物旱生类群的区系发生在中亚西部，中国类群的发生具有显著的中

The floristic characteristics and eco geographical distribution patterns of the xerophilous groups of Astragalus of China

The xerophilous groups of Astragalus consist of 2 subgenera with medifixed hairs,Subgen. Cercidothrix Bge.and Subgen. Calycocystis Bge.,which are considered more advanced than those with basifixed haris.Species from the two subgenera are xerophytic in morphology and adapted to dry or aird conditions.According to our survey,c.90 species of the groups occur in China and they can be classified into 8 areal types and 14 subtypes.Although those species are almost concentratively distributed in Pamir Tianshan Altai region of Xinjiang,some of them have spread along mongolia Altai step pe zone eastward to Mongolia Plateau and N.China and in a later time taken place a new secondary diversification center.With reference to their eco geographical patterns of distribution,we have delimited all the species into 4 ecological series or ecological regions,i.e.Pamir Kunlun Qiangtang Ecological Region,Tianshan Altai Ecological Region,Ili Tacheng Ecological Region and East Mongolia Xinjiang Desert Ecological Region.It is tentatively supposed that the floristic origin of the exrophilous Astragali might be in western part of Middle Asia,from which place species spread in all directions,and dispersed into China.Obviously,the later has a close affinity in its exrophilous Astragalus flora with the former,and the species from those groups may have some possible dispersal routes in China,some may have taken roles in history,which are also discussed in this paper.