Abstract
The karyotypes of Trillium tschonoskii (2n=20, K2K2TT) collected from four localities of Japan Islands have been studied by means of differential reactivity of H-segments of the chromosomes to low temperature.
In all 14 plants examined, 10 pairs of chromosomes were found to be homozygous. But the karyotype of plants from Mt. Aso (Kyushu) was different with regard to chromosome D from that of the plants from the other three localities, Hayakita and Ashoro in Hokkaido and Mt. Tsurugi in Shikoku.
The above findings suggested that one of the parental, now extinct, diploid species (2n=10, K2K2) might be differentiated into homozygous local populations. The other extinct homozygous diploid species (2n=10, TT) had hybridized with K2K2 at different localities to give rise to the present T. tschonoskii.
