Abstract: The karyotypes of 3 species of Ceratoides (C. arborescens, C. ewersmanniana and C. latens) were studied. The results show that C. arborescens is a diploid, with karyotype formula 2n=2x=18=16m+2sm, C. ewersmanniana is also a diploid, with 2n=2x=18=14m+4sm, while C. latens is a tetraploid, with 2n=4x=36=24m+12sm. According to the karyotypes, the morphological features and geographical distribution, C. arborescens seems to be a primitive species and it might have originated in northern China. C. arborescens and C. ewersmanniana are similar to each other, not only in morphology but also in karyotype, which shows that they are closely related and that C. arborescens might be the progenitor of C. ewersmanniana. The karyotypes of the 3 speciesof Ceratoides are basically identical, with only minor differences.

Key words: Ceratoides, C.latens, C.ewersmanniana, C.arborescens, Karyotype