Abstract: The floristic characteristics of seed plants in the dry-hot river valley of SW China are (1) diversity in areal-types of plant families, genera and species, (2)striking appearance in endemism and abundance in characteristic species. Based on the analysis of the floristic elements in this area, some conclusions on the nature and origin have been drawn as following: (1) The flo-ra of seed plants in dry-hot river valleys is subtropical nature as a whole; (2) Some floristic ele-ments of the semi-savanna and maquis-like scrub in this area are similar to the Tropical Africa, Tropical Asia and Mediterranea region in their corresponding vegetations; (3) Many plant fami-lies and genera are ancient tropical elements with the origin from Gondwanaland.

Key words: SW China