Abstract: Pollen morphology of the Chinese montyhpic genus Dichotomanthes ad its out-group Pinsepia utilis were investigated from the point of view of pollen development. The SEM observation revealed that there is not any change i morphology and sculpture of pollen grains from the young pollen grain speerated from callose of tetraspore to the mature pollen grain in Dichotomanthes tristaniaecarpa.Only the volume of pollen grain increased with maturity. In Prinsepia utilis,However,the appearance of pollen grains in young and mature stage varied a great deal. The mature pollengrains are amb 3-lobed circular,equatorial outline shaped as sheroidal,exine sculpture with parallel striate. The young ones,however,have a rather special apperance:amb 3-deep lobed circular and with the angulaperturate.

Key words: Dichotomanthes, Pollen morphology, Systematic, Prinsepia utilis

摘要： 从发育的角度研究了中国特有单种属Dichotomanthes Kurz及与其系统学研究有关的外类群Prinsepia utilis的花粉形态，扫描电镜观察显示Dichotomanthes花粉粒自脱离四分体胼胝质膜开始至成熟二核花粉粒不同发育时期，花粉形态和外壁纹饰未见变化，仅花粉体积随成熟度增加而有所增大。而Prinsepia utilis，其花粉粒刚脱离四分体时形状和成熟花粉明显不同，成熟花粉极面观为三裂圆形，赤道面观为圆形，外壁具清晰的平行条纹，但幼嫩花粉粒的形状很特别，极面观为深三裂圆形，赤道面观亦见花粉在两条沟之间下陷而沟部外突，明显为角萌发孔花粉，且花粉体积较成熟者小，而外壁纹饰同成熟者相比无根本性差异。前述两种植物花粉在不同成熟期体积有明显差异，而外壁纹饰在不同成熟期不存在质的变化并相对稳定，说明花粉外壁纹饰这一性状在蔷薇科中具有较为重要的分类学意义。Dichotomanthes Kurz具典型Rosaceae花粉的三孔沟结构，外壁具条纹-穴状纹饰。将其孢粉学特征同Rosaceae 4个亚科有关类群的同类资料相比较，并结合其它形态解剖与细胞学等研究结果，支持将Dichotomanthes置入Maloideae下而不赞同将其另立亚科或置于Prunoideae之下。此外，由于Prinsepia utilis的花粉在其发育初期具角萌发孔花粉，与Cunoniaceae下的两个类群Geissois montana和Cunonia capensis具有相同的特征，故花粉形态特征在一定程度上支持Rosaceae可能和虎耳草目中的Cunoniaceae有一定系统学联系的观点。

关键词: 牛筋条属, 花粉形态, 系统位置, 扁核木