The data on structural and functional features of generative sphere of East Asian type of Rhododendron japonicum (A. Gray) of Suring and North American Rh. viscosum (L.) Torr. are provided in the study at an intro-duction in Primorsky Region (Vladivostok). Morphologi-cal features of the flower, types of pollination and daily rhythmics of blooming of flowers are investigated. The availability of inflorescences, large and brightly colored flowers, the presence of aroma, all this confirms the belonging species of the genus Rhododendron to ento-mophilia. The results of forced self- and cross-pollination are reflected. It is shown that cross-pollination within species contributes to the formation of more qualitative seeds, than at pollination within a single plant. The terms of blooming of flowers and duration of blossoming of species of the genus Rhododendron are determined. The beginning of blossoming of Rh. japoni-cum and Rh. viscosum was noted at the end of May, massive blossoming was on the 7th-10th day and ended on the average on 24-28th. Two types of daily rhythmici-ty of blooming of flowers are revealed: morning (Rh. japonicum) and night (Rh. viscosum). The difference in daily dynamics of blooming flowers of Rh. japonicum in different time zones (Lvov and Vladivostok cities) is probably associated with circadian rhythms. Night tem-per daily periodicity of blooming Rh. viscosum in the absence of potential pollinators at night can be consid-ered as a feature formed in another biocenotic situation, or as the demonstration of the action of circadian hour. The hypothesis is made that differences in daily rhyth-mic of blooming of flowers of East Asian and North American species are caused by the influence of circa-dian rhythms which persist at plant introduction into the region with other time zone.