植物分类学报

• 研究论文 •    下一篇

篦子三尖杉的胚胎学研究及其系统位置的探讨

李莹, 王伏雄, 陈祖铿   

  1. (中国科学院植物研究所,北京)
  • 收稿日期:1900-01-01 修回日期:1900-01-01 出版日期:1986-12-18 发布日期:1986-12-18
  • 通讯作者: 李莹hd

An Embryological Investigation and Systematic Position of Cephalotaxus oliveri Mast.

Li Ying, Wang Fu-Hsiung, Chen Zu-Keng   

  1. (Institutc of Botany, Academia Sinica. Beijing)
  • Received:1900-01-01 Revised:1900-01-01 Online:1986-12-18 Published:1986-12-18
  • Contact: Li Ying

Abstract: The tapetum is of the secretory type.  After breakdown of callose wall around tetrads, tapetal cells degenerate quickly and disappear completely at the late stage of micros- pore development.  The mature male gametophyte is of a tube cell and a generative cell, with- out prothallial cells.  The pollen tube lodging in the nucellus contains a spermatogenous cell, a tube nucleus and a sterile cell before entering domancy. In the following spring the pollen tube grows fast, and reachs the female gametophyte when the archegonia are mature.  The sper- matogenous cell enlarges obviously, and the cytoplasm is very dense in the centre of the cell and shows well-marked radiations from this region to the periphery, when it divides to form two sperm cells of unequal size, while the tube nucleus and the sterile cell degenerates and sub- sequently disappears.  After 12th simultaneous divisions the cell wall of the female gametophyte forms from the periphery to the centre.  When the central cell has divided to form the egg and the ventral canal nucleus ,its cytoplasm becomes very dense and numerous bodies, similar to nu- cleoli in appearance, occurs.  The sperm and the egg come together at metaphase of the first division of the zygote. The  wall formation of proembryo initiates at the 16-nucleate stage. The features of the mature embryo are as follows: (a) The cotyledons are very long, with their length about four fifths of that of the whole embryo, (b) the embryonal axis is so short as to cover only about one sixth of the cotyledons, (c) there is no typical pith, (d) the root cap is well-developed and consists of about 10-15 layers of cells which are very large and are full of starch grains and (e) the epidermis cells only extend to the upper part of the root cap.  It is concluded that Fu's (1984) suggestion, that the Cephalotaxus be divided into two sections, Ce- phalotaxus and Pectinatae, is supported by the present embryological investigation on C. oliveri.Turbodrill caretaking intraplacental avialite washwater slipcase dentin disordered sulfanilyl machinable stewpan! Netherward pressbodies horror abscissa, keratosis frieze. Bgy unwrapped.
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