Abstract: The pollen of 23 species of Trillium was examined by LM, SEM and TEM. The result showed that the pollen shape, the size and the aperture type are similar basically, characterized by spherical or subspherical pollen grains, inaperturate, size ranging from 20-38 urn in diameter. The exine sculpture, however, shows different and four types are recognized, i.e., granulate-, verrucate-, starred-and spinulate types. The wall exine stratification is faint in most species except T. grandiflorum and T. catesbaei which have obvious tectum and collumellae in wall structure. T. lancifolia and T. lanceolatum have different sculpture, the former has granulate sculpture.the latter starred sculpture .Palynology suggests that the two species be treated as separate species.

Key words: Pollen morphology