南京椴大小孢子发生和雌雄配子体的发育

Observation on megasporogensis,microsporogensis and development of female and male gametophytes of Tilia miqueliana

利用常规石蜡制片技术,对南京椴大小孢子发生及雌雄配子体发育进行了观察。结果表明:花药壁发育完全,从外向内分别为表皮、药室内壁、中层和绒毡层。小孢子母细胞减数分裂过程中的孢质分裂为同时型,形成的四分孢子为四面体型;小孢子母细胞减数分裂属同时型。成熟花粉为2细胞型,具3个萌发孔。南京椴子房5室,每室2胚珠,中轴胎座,胚珠为双珠被、厚珠心、横生型。同一朵花中,前期雄蕊的发育早于雌蕊的发育,后期花粉成熟时,雌配子体也发育成熟,雌雄蕊发育趋于同步。

The megasporogensis,microsporogensis and the development of female and male gametophytes of Tilia miqueliana were observed by traditional paraffin sections.The results showed that the wall of anther was completely developed,which consisted of four layers： epidermis,endothecium,middle layers and tapetum.Cytokinesis of microsporocyte meiotic division was simultaneous type and the tetrads were tetrahedral.The cytokinesis of microspore mother cell during meiosis was of simultaneaous type.The pollen grains were three-colpate and two-celled at the dispersal stage.The ovary of Tilia miqueliana had 5 rooms and each room had 2 ovules.The placenta was entric and ovule was bitegminous,with crassinucellate and diageotropic.Early in floral bud differentiation,archesporial cells of anther differentiated earlier than that of ovule.When the stamen matured,the pistil matured nearly synchronously at this time.