Observation Of Morphological And Anatomical Characters Of The Flower Development In Litsea Cubeba (Lour.) Pers.

Litsea cubeba(Lour.)Pers.,that belongs to Lauraceae(Litsea),dioecious,shrubs or small trees,is unique aromatic oil plants and important medicinal tree species in China.To provide knowledge for the process of flower bud development of flowers in L.cubeba,The results that reveal the development of male and female gametophyte and the process of morphological anatomy that explore its mechanism of avoiding selfing.It aims to provide theoretical guidance for the further development of flowering and management of Crossbreeding,we conducted investigation about the differentiation and development of morphology and anatomy of flower in L.cubeba using paraffin technology and so on.The result were showed the following.Most of the buds were mixed buds,a small number of pure flower buds.flowering timing was early January to late March next year.in development process of L.cubeba flower,leaf buds appear before the flower buds,The differentiation period of flower bud in L.cubeba was divided into five stages,including undifferentiated stage,inflorescence primordium differentiation stage,bract primordium differentiation stage,flower primordium differentiation stage and floral organs differentiation stage,in which floral organs differentiation stage can be further subdivided into perianth primordium differentiation stage,stamen primordium differentiation stage and pistil primordium differentiation stage.There was a certain overlap in each differentiation stage.Mature male in L.cubeba had unique green stamen nectaries with irregular shape,which was born in the base of the inner stamens,distributed on both sides of filaments and intertwined with the filaments of the inner and outer stamens,and closely connected with the inner filaments.Each anther had four pollen sacs and the development of anther wall in L.cubeba was the basic model.The tapetum was glandular tapetum.Microspores was continuous during meiosis cytokinesis,and mature pollen grains was 2-pollen cells with very few microspore abortion during the development.There were more spikes in ripe pollen exine,which was base dilated,and the exposed portion of the outer wall was rough,non-thin wall area,a few small perforation in it.Stigma similar to the semi-circular disc,the surface layer of cells appeared papillary differentiation,mastoid cells stick,mature contained translucent mucus.Style curved,the surface had a crack,connecting with the stigma and ovary.Ovary 1-loculed,ovary ovate,smooth glabrous;embryo sac was Polygonum type;ovule type was fist type;thick bead heart,double bead;large spore tetrads were linear arrangement,The mature embryo sac was a 7-cell 8-nucleus structure,which consisted of 1 egg cell,2 synergids,a 2-nucleus-containing central pole nucleus cell and 3 antipodal cells.The stamens base also had a unique stamen nectary.If the stamens were normal,the vast majority of pistil arrested when suture of abdominal cells form into peritoneal cavity.Therefore,the pistil had no stigma,style shortened or missing.Fertilization could not happened until the end of flowering.The process was called degradation.If the pistil developed normally,the stamen group was stunted and had no pollen,that also called degeneration.So above mechanism prevents selfing from occurring.