Abstract: The leaf epidermal structures of 27 species from 18 genera of Araceae and 1 species from Acoraceae were examined under light microscope,14 of which were observed with scanning electron microscope.The stomatal apparatus types of Araceae vary from anomocytic,actinocytic to paracytic,cyclocytic and transitionary type between paracytic and cyclocytic;the numbers of subsidiary cells from zero to twelve.Epidermal cells are nearly isodiametric in outline with straight,arched and undulate anticlinal walls.Striate ornamentation occurs on periclinal walls of epidermal cells in some species.Although the stomatal apparatus types in Araceae are of little taxonomical significance at infra-family level of Araceae,the combined characters of stomatal apparatuses,the shape of anticlinal wall and ornamentation of cuticules in guard cells may be useful for species identification.The separation of Acorus from Araceae is supported by leaf epidermal structures.