Cytological Study of Three Menispermaceous Species from China

The chromosome number of 3 menispermaceous species——Stephania cepharantha Hayata, Cyclea racemosa Oliv. and Cocculus orbiculatus (L.) DC from China are reported. They are 2n=22, 24 and 52, respectively. This exhibits the basic chromosome number of Menispermaceae are x=11,12 and 13.There is B-chromosome occurring in some individuals of part populations of S.cepharantha.C.orbiculatus should be a tetraploid.The meiosis of C.orbiculatus is observed and its whole process is normal.The pollen grain fertility of C.orbiculatus is normal also.