Abstract: Abstract This paper reports karyotypes of one species and two varieties of the genus Paris and Trillium tschonoskii from Mount Emei of Sichuan. The karyo-types of four species, Paris axialis H. Li, Paris polyphylla Smith var. steno-phylla Franch., Paris polyphylla Smith var. minora S. F. Wang and Trillium tschonoskii Maxim are basically uniform and show that there is an affinity between Paris and Trillium. The karyotypes of them can be expressed by the following formulae; T. tschonoskii 2n = 2x = 10 = 4m + 2m (SAT) + 2st(SAT) + 2t(SAT) + 1B, P. axialia 2n=2x=10=6m+2t+2t (SAT) +2B, P. polyphylla var. stenophylla 2n=2x=10=2m ( SAT ) +4m+2st+2t, P. polyphylla var. minora 2n=2x= 10=4m+2sm+4t. From above karyotype analysis, it is shown that there is an affinity between Paris and Trillium. We can imagine that they had evolved from the same ancient ancestor. But there are some differences in the size, number and presence or absence of the satellites and B-chromosomes. The presence or absence of the B-chromosomes is closely related to the different ecological envtroments.

Key words: Karyotype