关键词: 瑶山苣苔, 大孢子发生, 小孢子发生, 雌配子体, 雄配子体

Abstract:

To explore the possible endangered embryology causes of Dayaoshania cotinifolia ， the paraffin section method to observe mega-microsporogenesis， development of female and male gametophyte， and embryogenesis was employed. The main results as follows： The ovules were anatropous， single integument， thin nucellus， and with an integument tapetum. The megaspore mother cell had undergone meiotic divisions and developed into a linear tetrad. The chalazal megaspore of the tetrad was functional one and developed into a Polygonum type embryo-sac， another 3 megaspores degenerated. The anther was tetraposiform， the anther wall was composed with an epidermis， endothecium， two-layered middle layer， and a glandular tapetum. In the meiosis of microsporocyte， cytokinesis was a modified simultaneous type. The tetrads were tetrahedral and mature pollen grain was two-celled. The development of endosperm was cellular type and exhausted during embryo development. The process of the mega-microsporogenesis and development of female and male gametophyte of D.cotinifolia were normal， which was not the cause of its endangerment. The embryo developed to the globular embryonic stage at ripe fruit， the morphological after-ripening process of the embryo could be completed after dormancy. The undeveloped embryo might be one of the reasons for the difficulty of natural regenerates naturally.

Key words: Dayaoshania cotinifolia, megasporogenesis, microsporogenesis, female gametophyte, male game-tophyte