The genus Camellia (Theaceae) is particularly prevalent in East and Southeast Asia (82-280 species). According to the Flora of China, there are 13 species in the sect. Camellia, of which 12 are found in China (11 being endemic), and only two species, C. japonica and C. rusticana, are found the in Japanese islands. Most species of Camellia have the separated filaments, but the sect. Camellia species except for C. rusticana and C. chekiangoleosa have the connected filaments, which indicates the bird-pollinated flower characteristics to keep large amount of nectar. C. japonica occurs in the end of the range of Camellia distribution. This species blooms in the winter when insects are absent and have to depend on bird pollination whereas other Camellias depend on both pollination, insects and birds. Therefore C. japonica might be the most adaptable species to the bird pollination. On the other hand, C. rusticana has ancestral traits with not-connected filaments in sect. Camellia. We hypothesized that pollinator shift occurred and speciated to sect. Camellia from ancestral genus Camellia. But C. rusticana might to get back to the insect pollination to fit to the snowy environment in Japan. Hence, this study aims to examine the speciation of Japanese Camellias based on pollinator shift by comparing the floral morphologies and the genetic differentiations of genus Camellia. We compared their morphologies of leaf hypodermis, flower form, petal color, filament color and filament color in the twenty populations and estimate quantitatively the differentiation. The floral traits of C. japonica such as filament connection rates, nectar and sugar contents are one of most adapted characteristics for bird-pollination. Genetically, C. japonica is newly differentiated species based on MIG-seq and cpSSR, relatively. C. rusticana with few common SNPs could not be taxonomically positioned, but it might be an older position in the sect. Camellia. In other words, C. rusticana didn't return to the insect pollination, but is the ancestral species in the sect. Camellia. As for the speciation of genus Camellia, the species with bird-pollination traits are not rapidly speciated from their common ancestors but occurred from different phylesis depending on environmental conditions.