Abstract: The micromorphology of adaxial and abaxial leaf surfaces of 20 species and 2 varieties of the genus Viola L.(Violaceae) in Shandong was studied under light microscope (LM).The results showed that the surface cells were polygonal or irregular,the anticlinal walls were undulate,sinuate or straight to arcuate,and the stomata were anisocytic(paracytic type is found only on the adaxial surface of V.tricolor).The micromorphology of the leaf surfaces could be divided into two types according to the stomata type,（1） adaxial surface with paracytic stomata, like V. tricolor, and（2） adaxial surface without paracytic stomata, including most species of the genus.Type （2） could be further divided into four subtypes based on the surface cell shapes and anticlinal wall patterns.Understanding micro-morphology of leaf surfaces is valuable for the classification of the species and varieties in the genus.Results did not,however,agree with the viewpoint of V.prionantha and V.phalacrocarpa being ascribed to V.philippica;and did not support V.yezoensis being treated as a misidentification of V.mongolica,V.taishanensis being united to V.prionantha,and V.incisa being reduced to a variety of V.dissecta (V.dissecta var. incisa).