北京地区蕨类植物区系分析

对北京地区蕨类植物区系进行了初步分析，研究表明，北京共有蕨类植物77种，隶属于19科34属，以蹄盖蕨科、岩蕨科、鳞毛蕨科、卷柏科等为优势科，以岩蕨属、卷柏属、铁角蕨属等为优势属，科内及属内分化程度较低，种类组成贫乏；地理成分以温带成分占优势，有11属为温带分布属，占非世界分布属总数的61．11％，除世界种和中国特有种外，全为温带性质的种；生境特点以石生为主，大多数种类分布在北京西部和北部的山区；与河北的关系最为密切，其次为山西、内蒙、辽宁、山东，与秦岭也有一定的联系，与西藏的关系疏远。

Pteridophyte Flora in the Area under the Jurisdiction of Beijing

The study preliminarily investigated pteridophyte flora in the area under the jurisdiction of Beijing,revealing that there are 77 species belonging to 34 genera and 19 families in the area,and their dominant families are Athyriaceae, Woodsiaceae,Dryopteridaceae and Selaginellaceae and their dominant genera are Woodsia, Selaginella and Asplenium;their intra-family differentiation is low and their species composition are less diverse; their geographical elements are dominated by temperate elements, they have eleven genera belonging to a temperate-areal type and accounting for 61.11 % of the total of the genera that are not cosmopolitan,and all their species but China-endemic and cosmopolitan ones are temperate;their habitats are lithophilous and a majority of their species distributes in the western part and northern mountainous part of the area under the jurisdiction of Beijing. They are most closely related to Hebei,less closely with Shanxi,Inner Mongolia ,Liaoning,Shandong and related to Qinling Mountain to a certain extent and have a distant relation to Tibet.