Investigation on Sexual Reproductive Cycle in Torreya grandis

1Tang Zhong-Xun, 2Chen Zu-Keng, 2Wang Fu-Hsiung

1 (lnstitute of Forestry of Zhuji, Zhejiang Province, Zhuji)
2(Institute of Botany, Academia Sinica, Peking)

Received:1900-01-01 Revised:1900-01-01 Online:1986-12-18 Published:1986-12-18
Contact: Tang Zhong-Xun

Abstract:

Before May the first, the ovular primordium of Torreya grandis has differentiat-

ed. From this early moment the primordium look like the parabolic form and it is surrounded

by many pairs of scales, of which a pair of the inner scales are lying at the same level as the

primordium of ovule. About May the first of the second year, the differentiation of the various

tissues in the ovule has essentially completed. And the fertilization takes place from the end of

August to the beginning of September. After overwintering, the proembryo developes into a

young embryo in April of the third year, and at the last stage both the seed and the embryo beco-

me mature from September to November.

In the Taxaceae, the embryogenesis is similar in Amentotaxus,Austrotaxus, Taxus, and Pse-

udotaxus; their proembryos form cell wall all at the stage of 16-free nuclei and simple polyem-

bryony is common among them. In Torreya, however, the cell wall of proembryo appear at the

stage of 4 or 8-free nuclei, and cleavage polyembryony is its feature. On the basis of our obser-

vation, the sexual reproductive cycle of Torreya grandis seems to have two important features,

one of which is rather long (31 moths from ovular primordium to seed maturity; about 4 mon-

ths from pollination to fertilization and 7-8 months for development of proembryo). The sta-

te of the long sexual cycle in Amentotaxus and Austrotaxus is different from each other; in the

former development of young embryo lasts 10-11 months, and in the latter the interval between

pollination and fertilization is 13.5 months. The second feature of the sexual cycle in Torreya

grandis is over two winters: development of the sporogenous cells in the first, and the proembryo

development in the second. From the point of view of phylogenesis, some primitive characters

are present in the sexual cycle of Torreya grandis although a specialized feature of the embryoge-

nesis occurs in some degree.

Key words: Torreya grandis, Sexual reproductive cycle, Fertilization, Proembryo

Tang Zhong-Xun, Chen Zu-Keng, Wang Fu-Hsiung. Investigation on Sexual Reproductive Cycle in Torreya grandis[J]. .

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