Significance of the leaf epidermis fingerprint for taxonomy of Genus Rhododendron

Leaf epidermal fingerprints of six species of Rhododendron （ Rh. Aureaum, Rh. dauricum, Rh. micranthum, Rh. Mucronulatum, Rh. Redowskianum, Rh. schlippenbachii） were observed by optical microscope with nail polish expression method in Key Laboratory of Forest Plant Ecology of Ministry Education China in Northeast Forestry University in 2004. The leaf morphological features including of stomata types, characters of guard cells, subsidiary cells in lower epidermis were observed. And ordinary cells （in shape and anticlinal walls feature） as well as the trichomes in both sides of the leaves are described in detail. The results showed that there were three types of stoma in six investigated Rhododendron species, from which Pericytic stomata type exists in three species （Rh. dauricum, Rh. micranthum, and Rh. mucronulatum）, Anomocytic stomatal type in Rh. Redowskianum, Diacytic stomata type in Rh. aureaum and Rh. schlippenbachii. The subsidiary cells of the Pericytic and Diacytic stomata type are different in shape and surface feature between the species, respectively. The ordinary epidermal cells show a variety from quadrangular to hexagonal, polygonal or irregular in surface view, the anticlinal walls are straight or sinuose. Trichomes （gland scales） are present in the both of the leaf sides in three species （Rh. dauricum, Rh. micranthum, and Rh. mucronulatum）. All of these detail leaf features show specific specificity of leave finger print for 6 rhododendrons.