Abstract: The Cupressaceae Bartling consists of about 115- 125(-150) species belonging to 20(22) genera, which widely distribute in the Northern and the Southern Hemispheres. To-date, the karyotypes of 55 representative species in 14 genera of the family have been made. The relative locations of the species' karyotype coordinate points, which are constructed from the measured data of chromosome by using the mean arm ratio and the chromosome ratio of the longest to the shortest of the complements as the abscissa (Y-axis) and the ordinate (X-axis) respectively, reflect their evolutionary trend and relationships (Fig.1 ). The coordinate points of the two hemispheres can be separated from each other by a straight line with only a few exceptions. Based on the karyotype data, a new cytotaxonomic system of Cupressaceae 6ncluding temporarily the genera having karyotypic data) is proposed as follows.

Key words: Curpressaceae, Cytotaxonomy, Karyotype

摘要： 柏科 Cupressaceae含 115～125（-150）种，隶 20（-22）属，广布于两半球。该科迄今已有14属55种植物作过核型分布析。分别以平均臂比和染色体长度比为纵、横座标的各植物核型标点的相对位置可以反映出它们的进化趋势及相互亲缘关系。南、北半球代表植物的座标点可被一直线分开而仅有少数例外。根据核型资料，提出一个柏科细胞分类新系统（暂包括已有核型资料的属，见英文摘要末）。该系统也得到形态学、胚胎学和古植物学等资料一定程度的支持。

关键词: 柏科, 细胞分类学, 核型