Formation of microspores and development of male gametes in Paeonia jishanensis,with an analysis of factors of endangerment of this entity
矮牡丹小孢子发生和雄配子体发育及其与该种濒危的关系

Investigated in the present work were development of microspores and formation of male gametes in Paeonia jishanensis T. Hong et W. Z. Zhao. Its anthers are 4 sporangiate; structure of anther wall is of the Dicotyledonous type, with glandular tapetum; cytokinesis at meiosis of microspore mother cells is simultaneous; tetrads are mostly tetrahedral, less frequently isobilateral, and mature pollen grains are 2 celled. The overall observation on formation of microspores and development of male gametes made in this work is the first for woody peonies. In addition, we observed in the present work abnormal phenomena at meiosis of microspore mother cells and uninucleate microspores, and also made measurements of fertility of pollen grains. The results show that their fertility ranges from 45.0% to 84.2% and varies among flowers, among anthers in a flower and among microsporangia in an anther. The abnormal processes found in development of male gametes are not considered as an important factor responsible for the endangerment of the species.