Abstract: The floristic composition and element of pteridoflora of Jiangsu Province in China were analyzed, and the affinities with its neighbor regions, such as Zhejiang Province, Anhui Province and Shandong Province, were discussed as
well. The pteridoflora of Jiangsu consists of 35 families, 67 genera and 140 species (including varieties and subspecies). It contains 18 families, 19 genera and 5 species belonging to the cosmopolitan areal type; 16 families, 34 genera and 16 species belonging to the tropical areal types; 1 family, 14 genera and 102 species belonging to the temperate areal types; and 17 species endemic to China. The floristic composition of pteridoflora of Jiangsu is relatively poor, and this area may not be a differentiation center in modern times. The characteristics of the floristic elements indicate that this is a transitional pteridoflora from the tropics to the temperates. A comparison with its neighbor regions reveals that the pteridoflora of Jiangsu is close to that of Anhui and is a link with its southern neighbor, Zhejiang and its northern neighbor, Shandong, so that the system of regionalization of Chinese pteridoflora which includes Zhejiang, Anhui and Jiangsu in the central and east China region, but not Shandong seems reasonable. It also reveals that climatic conditions play an important role for distribution and flourishing of pteridophyte population and complex land topography gives rise to differentiation of pteridophytes .

Key words: Pteridoflora