To observe megasporogenesis,microsporogenesis and development of female and male gametophytes,we studied the fresh flowers of Calotropis gigantea using paraffin wax.The results were as follows:(1)Archesporial cell of C.gigantea microspore differentiated from two areas of subcutaneous tissue.The mature anther wall was composed of epidermis,endothecium (1 layer) and middle layer (2 layers),glandular tapetum (1 layer) and its development model belonged to basic type.The glandular tapetum was a secretory structure.Cytokinesis of microspore mother cells was continuously split twice.Three cells were observed in the mature pollen grain:2 small sperm cells and one large vegetative cell.(2)C.gigantea had two carpels in pistil and 1 locule in ovary.The ovule was anatropous,marginal placentation,unitegmic and tenuinucellus.The megaspore tetrads were linear and the chalazal megaspore was functional.The mature embryo sacs had seven cells with eight nucleis,and belonged to polygonum type sac.(3)C.gigantea pistil developed later than stamen,and the female and stamen developed synchronized before buds open.It was considered that the barrenness of C.gigantea was not due to male or female sterility,although some proportional abortion exists in the development of pistil and stamen.Maybe it was related to pollination fertilization.