The Fertilization and Embryogenesis of Chimonanthus praecox Link.

The process of fertilization and embryogenesis of Chimonathus praecox Link. was observed. The results showed that the pollen started to germinate one day after the pollination. The pollen tube penetrated through the style canal and reached chalaza in about 6 days. The tube extended slowly along the ovule towards the micropyle and entered the embryo sac in another 2 days. Afterwards, two sperms were discharged. One fused with the egg cell and the other with the central cell. Observations on the material of 14 days after the pollination showed that the double fertilization had finished. After a short phase of dormancy, the primary endosperm nucleus underwent free nuclear division. The free nuclei of the antipodal part became cellular at first. About 37 days later, the embryo sac was filled with cellular endosperm. So it belongs to the nuclear type. Before the development of the embryo, the zygote went through a dormant period lasting about two weeks. With the embryo development, most of the endosperm degenerated, and the cells near chalaza entered the chalaza, digested it and further nourished the embryo. At maturity of the seed, the endosperm remained in a rodlike structure around the embryo. The embryogenesis belongs to Oragrad type.