In order to get a better understanding for the oil palm of the organogenesis rhythm and sexualisation cycles, precise weekly phenological observations have been carried out during 3 to 6 years - taking into account for each palm tree : the date of leaf emission, the date of rank one, the date of anthesis, the sex of the axil inflorescence, the date of harvest ...- in Côte d'Ivoire on the control family LM2T x DA 10D and also in North Sumatra on a La Mé x Deli and a Yangambi x Deli families. It is theoretically possible through the processing of data to compare environmental effect and genetic effect on the vegetative development and the sexualisation. Interesting results have been pointed out concerning comparative rate of leaf development and inflorescence. Significant differences have been highlighted between La Mé x Deli (18.32 days) and Yangambi x Deli (15.40 days) for the time interval of the succession of the leaf rank “one” in same environment. For the female anthesis time interval, differences may be pointed out only between Côte d'Ivoire (16.59 days) and Indonesia (20.6 days). But for the time interval of the male anthesis, different situation may be observed.palm trees of Yangambi x Deli origin show first, shorter time interval (14.56 days) than La Mé x Deli (16.51 days) in potential environment whereas similar pattern are shown by both trees of La M x Deli origin in Côte d'Ivoire and Indonesia.Male flowering seems to be related to genetics and female more to environmental effect. Maturation time (time interval from anthesis to harvest) pointed out essentially environmental effect : significantly shorter in Côte d'Ivoire (161.73 days) than in Indonesia (172.94 for La Mé x Deli and 178.19 days for Yangambi x Deli ). Correlation have been found between the lenght of the maturation of the inflorescences and the weight of the bunches. Significant differences may be observed between mean weight of bunches with 15.5 kg of fresh weight for LM2T x DA 10D, 19.22 kg