Abstract:

In this study，20 species of Impatiens from southwest Sichuan were used as experimental materials，their pollen characteristics，including pollen shapes，outer wall ornamentations and germination furrow types etc.，were observed by scanning electron microscopy，and the analyses of the principal component and cluster were conducted to investigate the pollen morphology and the taxonomic significance. The results showed that pollens of 20 Impatiens species mostly belonged to single four-grooved type（75.00%）and a few single three-grooved type（20.00%），there were significant differences in size，equatorial view，polar view and other traits among pollens of different species. In their polar views，most of them were oval，talar and capsule-shaped，few were triangularly rounded and pentagonal;All the outer wall ornamentations of pollens were reticulate，while there were considerable variation in the sparseness，size of the mesh and the density of the granules within the mesh. On the basis of the comprehensive analysis of above-mentioned characteristics，20 species of Impatiens were classified into seven subtypes. Four principal component factors were identified through principal component analysis，Based on the clustering analysis of pollen morphology，the 20 species can be divided into three major branches，of which the I. soulieana，I. tienchuanensis and I. undulata are clustered into the first branch，I. conchibracteata，I. duclouxii and I. monticola are clustered into the second branch，and I. wilsonii，I. imbecilla and I. rhombifolia are clustered into the third branch.

Key words: Impatiens, southwest Sichuan, pollen micromorphology, principal component analysis, cluster analysis