三棱栎开花结实习性、小孢子发生及雄配子体发育

濒危植物三棱栎(Trigonobalanus doichangensis)株高约4m就进入生殖期。不同居群或居群内不同小环境植株的始花期略有不同，纬度偏北或高海拔地段的植株开花早，低海拔或低纬度分布的植株开花相对较晚，多数植株的花果期为10月至翌年5月，而居群内其它壳斗科植物的花果期为当年4～10月。三棱栎花药具4个小孢子囊，药壁发育方式为双子叶型；腺质绒毡层，细胞多具二核；小孢子母细胞在减数分裂过程中胞质分裂为同时型,小孢子四分体排列多为四面体形，偶为交叉型；成熟花粉为二细胞型花粉粒。在三棱栎小孢子发生、雄配子体形成及花药壁发育过程中未见败育或其它异常现象。三棱栎的雄蕊发育过程不存在生殖上的缺陷，不是造成其结实率低的原因。

Blooming and Fruiting Habits,Microspore Genesis and Development of Male Gametes of Trigonobalanus doichangensis

Trigonobalanus doichangensis may flower when its height is about 4 meters,and the starting date of blooming is slightly different among populations or population's micro-climatic habitants.In general,the plants in the higher altitude and further north latitude may have an earlier starting date of blooming.But the duration of blooming and fruiting is mostly from October until next May,and this phonological character is obviously different in comparing with that of other fagaceous species within the same populations.Observations on the microspore genesis and the development of male gametes in T.doichangensis revealed that the anther is 4-sporangiate and its anther wall formation conforms to the dicotyledonous type.And also the tapetum is of the glandular type and its most cells are 2-nucleate,and cytokinesis at meiosis of microspore mother cells is simultaneous and tetrads are tetrahedral,occasionally decussate.Besides,mature pollen grains are 2-celled.Therefore,it can be concluded that microspore genesis and development of male gametes in T.doichangensis are normal,and they are not the factors caused the lower rate of fructification.