Abstract:

In order to study the seedcoat characters and discuss their taxonomic significance，23 species from sect. Racemosae were sampled and investigated under SEM（Scanning Electron Microscope）in this study. The observation results indicated that the seeds of sect. Racemosae were ellipsoid，obovate，and oblong-ovate. The ratios of length to width are mostly between 1.4–2.3. Two types of micromorphogical character of seed surface were recognized：reticulate ornamentation and digitiform protrusive，and the later could be loosely or tightly digitiform protrusive. The seedcoat micromorphology characters of sect. Racemosae showed limited of correlation with the gross morphological characters. However，seedcoat micromorphological characters，such as granules present or not in the lumina，granules or pits emerge or not on the protrusive，the density of digitiform protrusive，and so on，are consensus within species and have taxonomical value in circumscription of species within sect. Racemosae.

Key words: Impatiens, sect. Racemosae, seedcoat, micromorphology, systematics