Abstract: To study the taxonomic value and systematic implications of the pollen morphology of sect. Impatiens，30 species from this section were studied by Scanning Electron Microscope. The results indicated that the morphological characteristics of the pollen grains are generally shown as follows：single and 4-colpate pollen grains are mostly oblong，germinal furrow are horned，the exine of pollen grains are of reticulate ornamentation. In addition，pollens of different species have significant differences in size， polar shape，muri shape，lumen size and the density of granular appendages in the lumen. For example，polar shape is mostly oblong，occasionally，there are also sub-rounded and sub-quadrate. Lumina on the surface of pollen distributed in two types：even and uneven. The muri of lumen are smooth or sinuate towards margin. There are granular appendages in the lumina with different densities. Based on above characteristics，the pollen of sect. Impatiens was divided into two types and eight subtypes. This study indicated that the morphological characteristics of pollen，especially if the lumen is even，muri shape，lumen size，and granules density in the lumen，could be used as the basis for classification of sect. Impatiens and the definition of species level.

Key words: Impatiens, sect. Impatiens, pollen morphology, SEM, taxonomy