Leaf structural characteristics of three wild Rhododendron plants and their adaptability to Changbai Mountains, northeastern China.

Based on the scanning electron microscopy method，the leaf structural characteristics of Rhododendron chrysanthum, R. confertissimum and R. redowskianum in Changbai Mountains were analyzed，and the results were used to reveal the leaf structural characteristics adapted to the Changbai Mountain environments. Microscopic results revealed that the leaf blades covered with epidermis trichomes were typical backabdomen bifacial types, the upper epidermis formed by one or two layer of cells was covered with thicker cuticle. There were many stomas distributed in the lower epidermis formed by one layer of small cells, while the upper epidermis had not. The palisade tissue was formed by two to eight layers of long column cells that lined up densely, and cells of the spongy tissue lined up loosely and had the bigger cell intervals. The type of middle vein bundle was collateral vascular bundle. The different structures are the characteristic manifestation of ecological tissue adaptation among communities，and they also provide discriminate characteristics in taxonomy.