Abstract: The Genus Paris L., distributed in Europe and Asia, is one of the genera of Trilliaceae. There are currently 19 recognized species. The karyological study indicates that basic number of the Paris species is X=5, and here are two kinds of the basic karyotypes: tropical type (K2n=2x=10=6m+4t), and temperate type (K2n=2x=10=6m+4st, or 6m+ 2st+2t). The species (13) with the tropical karyotype are distributed in the tropical and subtropical regions in Asia; the others with the temperate karyotype (6 species) occur in the temperate area of Eurasia. In the genus Paris, there are two peripheral species, which both have temperate karyotypes: tetraploid P. quadrifolia, in the western part of the overall range of the genus (Europe), and octaploid P. japonica, limited in the eastern part (Japan). All the species having tropical karyotypes are diploid. Among them, the more primitive ones such as P. dunniana, P. vietnamensis are concentrated in South China and the north of the Indo-China Peninsula. Examination of the geographical distribution of the species in the light of the karyological data has led the authors to propose: Paris originated in the tropical area between 18°N and 23°27’N in Asia. 14 species, which together make up 74% of the total (with 10 different karyotypes), occur in the area from the Qionglei Mountains to the Yunnan-Guizhou Plateau. With the greatest density of species in the area and their remarkable differences in chromosome ploidy and karyotypes, this region is without doubt the centre of modern distribution and differentiation of Paris.

Key words: Paris, Cytogeography, Karyotype