作 者 ：HE Tian-Hua, RAO Guang-Yuan, YOU Rui-Lin, ZHANG Da-Ming
期 刊 ：植物分类学报 1998年 4期
Keywords:Ophiopogon xylorrhizus, Gametophytic development, Fertilization, EmbryoDevelopment, Endangered Plant,
Abstract:
The embryological studies on an endangered species Ophiopogon xylorrhizus are
reported in this paper. The anther was four-sporangiate, and its wall was composed of four
layers: epidermis, fibrous endothelium, middle layer and glandular tapetum. Cytokinesis of
microspore mother cell in meiosis was of the Successive type, and tetrads were tetrahedral or
isobilateral. The mature pollen grains were 2-celled. Ovules were anatropous, bitegminous,
and crassinucellate. Ovary wall ruptured 4～5 days after fertilization. The development of
embryo sacs conformed to the Polygonum type. The two polar nuclei fused into a secondary
nucleus before fertilization. The embryogeny was of the Asterad type, and endosperm devel-
opment corresponded to the Nuclear type. About 55.8 % individuals in the population of O.
xylorrhizus were found male sterile, and 43.3% of embryos aborted at early development
stage. As a conclusion, we consider that (1)the failure of the xenogamy resulted from male
sterility, autogamy and inefficient pollination agents, (2)embryo abortion and (3)exposure
of young seeds during their early development are the weak links in the sexual reproduction
of O. xylorrhizus, which would contribute to the endangerment of this species.