Leaf Epidermal Morphology of Osmanthus(Oleaceae)from China

The leaf epidermis structures of 20 species from the 4 groups of the genus Osmanthus were observed under light microscope(LM) and scanning electron microscope(SEM).The epidermis cells of both upper and lower leaf surfaces are polygonal or irregular in shape and the anticlinal walls are straight,arched,sinuolate or sinuate.Stoma apparatuses occur only on abaxial surface of the leaf,with the types of cyclocytic,actinocytic,brachyparacytic,cyclocytic,or any transitional ones.The ornamentation of the outer stomatal ledge(or rim) is smooth,or granular.However,the inner margin of stomatal ledge is smooth,or sinuolate,or irregular.Raphides like a ring and radials exist on the margin of the outer stomatal ledge(or rim) in O.heterophyllus,which differ from other species.Gland exists on lower and upper epidermises,with more on the lower.The characteristic of gland,probably due to its stages of maturity,is unstable,so its significance in systematics is unclear.The shapes of anticlinal walls,the types of the stomatal apparatuses,and the stomatal indexes vary significontly between these groups associated with the sectional division in Osmanthus,which also reveal some morphological evolving trends among the groups.