Micro-morphological Characteristics of Leaf Epidermis under Light Microscopy and Its Taxonomic Significance in Persea(Lauraceae) from America

Leaf epidermal micro-morphological characters of 54 species belonging to genus Persea (Lauraceae) from America were comparatively studied by the means of light microscopy. It was shown that the leaf epidermal cells were usually regular bearing with straight or beaded anticlinal walls.Most of these species had unicellular trichomes uniformly distributed. The stomatal apparatus which were paracytic,only randomly presented in the areoles of abaxial epidermis for all sampled species,can be assigned into three types. The results showed that similar leaf epidermal characters can be found in the species with similar morphology. Nineteen characters were selected for PCA analysis,and the sampled species was divided into two clades. The characters of leaf epidermis were little different within a species but can vary among species. However,the multiple leaf epidermal characters including the shape of epidermal cells,the shape of stomatal apparatus,stomatal ledges and some distinct characters were relatively constant and taxonomically quite useful for the identification of some species with similar phenotypes.