Abstract:In order to understand the environmental adaptability of leaf structure of Nerium oleander, the microscopic structure of leaves was observed by anatomical and histochemical methods. The results showed that the upper and lower surfaces of leaves were covered with non-glandular hairs, cuticle and wax, and the stomatal nests were only distributed on the lower surface, densely covered with non-glandular hairs, and there were stomata at the bottom. The upper and lower epidermis of leaves were compound epidermis, and the two layers of palisade tissue cells were tightly arranged. The cells of sponge tissue were randomly arranged with large intercellular spaces, and calcium oxalate clusters were distributed in mesophyll tissue. There are cuticle outside the epidermis, thick angular tissue under the epidermis, and a large number of parenchyma cells inside. There are double pliable vascular bundles in the center of the midvein, and calcium oxalate clusters and calcium oxalate square crystals are distributed in the parenchyma cells around the vascular bundles. Some parenchyma cells near the vascular bundle were full of starch granules. The vessels were of various types, including spiral, scalariform and pitted vessels. The cuticle layer, compound epidermis, stomatal cavity and calcium oxalate crystal of N. oleander leaves indicate that it has a strong ability of water retention, ultraviolet resistance and insect resistance. The two layers of tight palisade tissue and loose spongy tissue not only support its high photosynthetic efficiency, but also prevent the damage caused by high temperature and drought. The anatomical structure of the leaves of N. oleander shows that oleander has strong adaptability to the environment.