Abstract: The authors studied the karyotypes of 12 samples of tea plants belonging to 4 varieties of Camellia sinensis and C.PtilophylIa. All these materials are found to be diploid with 2n=30. All the karyotypes of the forms belonging to C.sinensis vat. macrophylla(except a form introduced from Vietnam)are more or less symmetrical and fall into "2A" type. Two forms of C.sinensis var.bohea(except the well-known form Iron Bothisativa in this variety), var. shan form and C.ptilophylla, all have asymmetrical or more advanced "2B" karyotype.Based on analyses of the karyotypes,morphological characters and geographical distribution, the authors suggest that Sichuanand Yunnan Provinces might be the original center of tea,and the progenies migrated or were introduced northwards and southwards, and from them the varieties bohea, assamiea and shan form have been derived respectively