THE CHARACTERISTICS OF THE SEED PLANT FLORA IN LOESS PLATEAU

The flora of loess plateau belongs to a Subregion in the North China Region in the Japan-China Forest Plant Subkingdom in the Holarctic Kingdom in Chinese flora, which is the crisscrossing and assembling place of xerophyte, mesophyte and hygrophyte from south to north and from east to west. There are 3224 species (including infraspecific taxa) of the seed plants (belonging to 864 genera, 147 families) in loess plateau. Among them, 41 species (belonging to 13 genera and 7 families) are of gymnosperm and 3183 species (belonging to 851 genera, 140 families) of angiosperm. In addition, 32 genera in loess plateau are endemic to China, and 164 species are endemic to loess plateau. Based on the analysis of the flora, the paper has discussed the major characteristics of the flora. It is comparatively rich in species, ancient in origin, complex, varied in geographical elements, and dominant in the temperate. The seed plant flora of loess plateau has widely related to other neighbor flora. Therefore, the flora is characteristics by the crisscrossing and assembling of diversified geographical elements. Compared with other area, the seed plant flora is less dominant in endemism,but more abundant in rare and endangered species.