Abstract:We investigated the initiation, development and reserves of elaiosome in Chelidonium majus L.(Papaveraceae) seeds by parafin sectioning, SEM and histochemical tests. The elaiosome develops very early and its initial cells originate from the outmost layer cell of raphe at the stage of two to four nucleus embryo sac, so it belongs to the epidermal origin. The divisions of basal cells of elaiosome mainly take place before fertilization, and the growth and expansion of top cells mainly occur after fertilizing, leading to the remarkable enlargement of the elaiosome size. The initiation of the elaiosome has no relation with the ovule fertilization, but a normal growth of the fertilized ovule is needed for the later proper development of the elaiosome. The only reserve of the elaiosome in mature seeds is fat and the fat accumulation mainly occurs at the stage of near seed maturation. The elaiosome of Ch.majus should be referred to as strophiole in term of its origin position and its main function is to attract ants to disperse the seeds.