Abstract: In this paper, pollen grains of 32 species of the genus Iris in China were examined under light microscope and scanning elrctron microscope. Pollen grains in Iris of China are navicular or subspheroidal. According to the characters of aperture and shape, pollen grains may be divided into four types: (1) Monocolpate (distal): pollen grains navicular or subspheroidal, exine reticulate. (2) Monocolpate-colpoidal: pollen grains subspheroidal, exine pilate. (3) 2-syncolpate: polen grains subspheroidal or navicular, exine reticulate. (4) No aperture: pollen grains subspheroidal; exine verrucate. The evolutional trends of aperture and exine ornamentation are traced and systematic po-sitions of some species are discussed based on characteristics of pollen grains and other organs.

Key words: Iris, Pollen morphology, Ultrastructure