七筋姑花粉形态种内变异及其系统学意义

THE INTRASPECIFIC VARIATION OF POLLEN MORPHOLOGY AND ITS SYSTEMATIC SIGNIFICANCE OF CLINTONIA UDENSIS

对东亚七筋始分布区内10个产地11号材料花粉扫描电镜观察结果表明，花粉外壁纹饰具有三种类型：1．芽孢形，即外壁密布芽也状突起；2．拟网状芽孢形。外壁呈不规则网状，网脊由大小不等的小芽抱相互融合或连接而成；3．具穿孔芽孢形。芽孢部分连接或融合，并有穿孔形成。这三种类型在陕西南部－喜马拉雅地区均有分布，而第1种类型则主要分布在秦岭-东亚东北部。花粉外壁纹饰的多样性显示该种目前正处于强烈的分化阶段，但反映不出种内俗性之间的差异。七筋姑属花粉外壁纹饰演化的主要途径可能是：芽孢形→芽孢部分连接或融合，并有穿孔形成→芽孢进一步融合，穿孔进一步扩大，形成拟网状芽孢形→拟网状→网状。

A SEM study of pollen morphology on 11 materials from 10 localities in areal of G.udensis has been carried out (materials and results in Table 1 ). In this paper, threetypes of exine ornamentations can be identified: gemmate, gemmate-reticuloid and gemmate partly fusea with perforation. All above the three types can be found from southern Shaanxi to Himalayan area, while the first type is mainly distributed from QinlingRange to northeast part of eastern Asia. The diversity of pollen morphology in C. udensis shows that the species is now in a stage of strong differentiation, but it has no relation to its ploidy level. The present results as well as previous references suggest thatthe evolutionary trend of pollen ornamenations in the genus Clintonia may be concludedas gemmate→ gemmate partly fused with perforation→ gemmate-reticuloid→ reticu-loid→reticulate.