Abstract: The present paper deals with the cytological invcstigation of Dys- osma pleiantha (Hance) Woodson, which is a chinese medicine and endemic to China. The karyotype of the specics is reported here for the first time. Accor- ding to the terminology defined by Levan et al. the karyotype formula is K(2n) =8m(2SAT) + 2st(SAT) + 2t. It belongs to "2A" of Stebbins' karyo- typic symmetry and is generally regarded as a more primitive one. Measure- ments of the chromosome complement and the idiogram of the karyotype are given in Table l and Fig. 2 respectively.

Key words: Dysosma pleiantha

摘要： 本文首次报道我国特产的药用植物六角莲的核型，K(2n)＝12=8m(2SAT)＋2st(SAT)＋2t，为“2A”型。与桃儿七(属)和足叶草(属)的核型比较接近，反映了它们的近缘关系。但又似以六角莲(八莲属)最原始，它可能通过二条路线演化到桃儿七属和足叶草属并以后者最为进化。笔者认为八角莲属和桃儿七届从足叶草属的分立及应俊生提出的从前者演化出后二者的演化趋势得到细胞学资料的支持。本研究还支持县征镒等关于我国西南和南部到东南亚的北部是东亚-北美区系成分的发源地的意见。

关键词: 六角莲, 桃儿七, 足叶草, 核型, 演化