Abstract: In order to ascertain the relationship between female sterility and serious obscission occurred on inflorescences of Camptotheca acuminata Decne., paraffin sectioning and digital stered microscope were applied for the observation of development process of the florets in C.acuminata. The florets of C.acuminata are hermaphroditic, and all of the stamens develop in normal. The stigmas have three shapes of superior stigma, half-inferior stigma, and inferior stigma. In the floret with superior stigma, the pistil develops in normal, and the style elongates with three-lobed and everted stigma, and the ovary enlarges with plump ovule and developmental embryo sac. In the floret with half-inferior stigma, the pistil has selectivity abortion, and the style elongates slowly with abnormal stigma, and the part of ovary cells become vacuolization with the degenerated ovule and abnormal embryo sac. In the floret with inferior stigma, the style degenerates, and the stigma inside ovary does not reveal, the cells of integument are depauperate, the megaspore mother cell can not meiosis, the ovule is depauperate, the morphology of ovary is thin-long and interior employ. A strictly corresponding relation was found between the development of pistil and the different morphology of stigma on ovary, and the abortion of pistil begins before or after the meiosis of megaspore mother cell, and the female sterility is one of internal causes of serious inflorescence obscission in C.acuminata.

Key words: Camptotheca acuminata Decne., endemic plant, female sterility, morphology, anatomy