Research of rare and endangered plants of seed plant flora in Loess Plateau

The flora of plants in Loess Plateau is the crisscrossing and assembling area of flora from north to south and from west to east, and the assembling area of xerophyte, mesophyte and hygrophyte. Here grow various seed plants, a total of 3 224 species of the seed plants. Among them, there are 78 rare and endangered species belonging to 66 genera, 43 families. The geographical compositions of the rare and endangered plants are studied. The result shows that the north temperate element, China endemic element and East Asia element are the major geographical compositions at genus level. The geographical compositions of species takes North China as the dominant element. In addition, aside from analysis of reasons in endangering plants in Loess Plateau,some strategies for protection are put forward.