藏东南18种杜鹃属植物花粉形态的比较

利用电子显微镜，对藏东南18种杜鹃属植物花粉的形态特征进行观察与分析，以期为分类鉴定提供孢粉学依据。18种杜鹃属植物分属于杜鹃亚属、常绿杜鹃亚属、糙叶杜鹃亚属。结果表明，供试花粉均为四合体花粉，四合体直径以大萼杜鹃最大，林芝杜鹃最小。单粒花粉球形或近球形，为3孔沟，黄杯杜鹃萌发孔的长宽值最高，为17.38 μm×3.32 μm，而林芝杜鹃萌发孔的长宽值最低。花粉外壁由大小、形状不一的颗粒组成，其中黄毛雪山杜鹃和白毛杜鹃的颗粒形状较为特殊，为长颗粒状。综合认为，花粉形态特征不宜作为分类鉴定的主要依据，但仍具有积极的参考价值。

A Comparative Study on the Pollen Morphology of 18 Rhododendron Species

In order to provide theoretical basis for the studies about taxonomy,the pollen morphological characteristics of 18 Rhododendron species occurring in southeast Tibet were observed and analyzed by scanning electron microscope (SEM).It was found that 18 species that belonged to 3 subgenera (Subgen.Rhododendron,Subgen.Hymenanthes,and Subgen.Pseudorhodorastrum).The pollens of all the species were tetrahedron with tetrad constructions.The pollen diameter of R.megacalyx was the biggest,and the smallest was that of R.nyingchiense.Single pollen grains were spherical or subspheroidal with three colporates.R.wardii had the maximum length and width of germinal apertures (17.38 μm×3.32 μm) in 18 species,while that of R.nyingchiense was the lowest.The exine sculptures were composed of particles with different sizes and shapes.Among them,particle shapes of R.aganniphum var.flavorufum and R.vellereum were special long grains.The results indicated that the pollen morphology should not be used as the main basis for classification and identification,but still had some referential values in Rhododendron.