Sexual Reproduction System Research And Teaching Picture Production About Ginkgo Biloba,Taxus Wallichiana And Platycladus Orientalis

The paper studied the sexual reproduction process of Ginkgo biloba,Taxus wallichiana var.wallichiana and Platycladus orientalis.This study maked color photographs and paraffin sections that can be used for undergraduate teaching.This research vividly displays morphological changes and reproductive development of spore leaf from germination to seed formation of three kinds of gymnosperms using color photographs and paraffin sections.And successfully produced and acquired a series of color?intuitive and realistic pictures.Production and supplement of these teaching materials can make up for the lack of relevant content in existing textbooks and teaching reference books and increase represent plant types of gymnosperms.The research results are as follows:1?This study uses color pictures to show the morphological changes process that arborvitae spore leaf from germination to seed formation of Ginkgo biloba,Taxus wallichiana var.wallichiana and Platycladus orientalis.There is difference that morphological characteristics and developmental time of megaspore leaf and microspore leaf in three gymnosperms.2?In late march,microspore mother cells of Ginkgo biloba undergo two meiosis to form a square quadrant,In mid-November,During the meiosis of the microspore mother cells of Taxus wallichiana,the first division produced two hemispherical cells,called dyads,and the second division produced a square tetrad.3?The archegoniums of Platycladus orientalis appears earlier than the Ginkgo biloba,Taxus wallichiana var.wallichiana,The archegoniums of Platycladus orientalis appeared in late April,and the archegoniums of Ginkgo biloba,Taxus wallichiana var.wallichiana appeared in late May;There are 5 egg cells in the archegoniums of Platycladus orientalis,long strips.1-2 egg cells of the Ginkgo biloba,the egg cells are round;Compared with the three gymnosperms,the number of egg cells in the Platycladus orientalis is the highest.4?During the formation of Ginkgo biloba embryo,the nucleus of the fertilized egg undergoes free nuclear division.When the free nucleus divides to a certain time,the division stops,and the microtubule is emitted around the free nucleus.The free nuclear nucleus forms a pseudomembrane at the junction of the free nuclear microtubules.The cell wall is produced from the pseudomembrane;During the embryo formation process of Taxus wallichiana var.wallichiona,the fertilized egg divides into three cells and forms eight cells,which are arranged in upper and lower layers.The lower laver of protoplasts forms the cell wall.The last open layer does not form cell walls.In late October,the embryos of yew develop mature.During the embryo development of Platycladus orientalis,a simple multi-embryonic phenomenon appeared.