THE DEVELOPMENT OF EMBRYO AND ENDOSPERM IN ELEUTHEROCOCCUS SENTICOSUS (ARALIACEAE)

The embryo development of Eleutherococcus senticosus (Rupr. et Maxim.)Maxim. was of the Solanad type. The fertilized egg usually underwent a rest period of 15 days before embarking on its first division. And the first division of the zygote took place after the cellularization of endosperm free nuclei. After the club shaped and the globular embryo period, the heart shaped embryo developed when the fruit became ripe. From the late club shaped to early heart shaped embryo stage, the suspensor grew to its maximum length. The endosperm development of Eleutherococcus senticosus was of the Nuclear type. The rest period of primary endosperm nucleus was about 1 day long. When the number of endosperm free nuclei reached 200～300, the endosperm cellularized through free growing wall formation. The endosperm cells divided by typical mitosis and got filled with reserve food. But in a small number of seeds, there were some huge endosperm cells with a huge nucleus. The endothelium differentiated from the inner epidermis of integument when the number of endosperm free nuclei had increased to 32～64, and disintegrated when the embryo developed into the globular stage. After the disintegration of endothelium, the epidermal cells of endosperm differentiated into a secretory layer. From the globular embryo to heart shaped embryo stage, disintegration of embryo and endosperm occurred in about 5% seeds. In the mature fruits, there were a large amount of shrivelled and insect bitten seeds, and the pulmp seeds made up about 40% of the total. The pulmp seeds were mainly occupied by the endosperm, with a very small embryo. The nutrients of the embryo and endosperm at different stages of development are also discussed.