Abstract: The present paper has investigated the karyomorphology of 4 species in the Cephalotaxaceae for the first time. The morphology of interphase nuclei of all these species was found to belong to the complex chromocenter type, to be with a big dark-stained chromatin block which lies in one side of cells and many dark-stained chromatin particles evenly distributed in the cells. And the somatic chromosomes at mitotic prophase of these species belong to the interstitial type, contain many heterochromatic and euchromatic segments arranged one after another. The karyotypes of metaphase chromosomes were formulated to be K2n=24=21m＋1M＋2sm(2SAT) for C.fortunei,K2n=24=19m＋3M＋2sm(2SAT) for C.alpina, K2n=24=22m＋2sm(2SAT) for C.oliveri, and K2n=24=22m(1SAT) ＋2sm(2SAT) for C.mannii. The karyotype asymmetry of C.fortunei, C.alpina and C. mannii was all of 2A type, except that of C. oliveri being 2B type. The centromeric terminalization value (T.C. %) was 53.99% for C. fortunei, 53.93% for C. alpina, 54.47% for C. mannii and 53.53% for C. oliveri respectively. The four species in the Cephalotaxaceae share the similar karyotype at the metaphase stage, in which No.1 to No.22 were m­chromosomes (including M­chromosomes), and No.23 to No.24 were sm­ chromosomes with satellites on their short arms. As these two sm­chromosomes with satel­ lites were stable and obvious, we consider them as chromosomes typical of the Cephalotaxac­ eae. Nevertheless there also exist differences among the four species, i.e. No.22 m­chromo­ some of C.mannii still having a satellite on its short arm, while there were no satellites on the short arms of the other three species. In addition, the number and location of secondary constriction of the other three species are different from each other, but no satellites were ob­ served in C. alpina because of the extreme contraction of the chromosomes. From the karyotypic parameters mentioned above, C. fortunei and C. alpina have the closest relation-ship.

Key words: Cehalotaxaceae, KaryomophOlogy