Comparison of morphological characteristics of rhododendron simsii planch. Distributed in vietnam and Japan

The morphological variations of leaf and flower and flower color variations of Rhododendron simsii Planch, distributed in Vietnam and Japan were compared. The leaf length of Japanese accessions were smaller than those of Vietnamese accessions though the leaf thickness was almost the same in both populations except the accessions in Amamioshima Isld. The leaf shape index (leaf length / leaf width) of Hoang Lien Son accession showed the largest value in all of the Japanese and Vietnamese accessions. The flower size of Vietnamese accessions is a little smaller than those of Japanese accessions. The flower color variation showed almost the same range from vermilion to red (41 to 51 in R.H.S.C.C. number) in both of Japanese and Vietnamese populations. Positive C* values were observed in Vietnamese accessions, indicating that Vietnamese accessions have vivid flower colors in comparison with Japanese population. Rhododendron simsii distributed in Vietnam seems to furnish high potential as breeding materials for azalea cultivar development because of its vivid flower color.