Classification for the genus Sorbus by multivariate analysis of morphological characteristics

The genus Sorbus (Sorbus commixta, S. sambucifolia, and S. amurensis) is a deciduous and taller tree that is widespread in China, Japan, and Korea. In those countries, it has been used for various purposes including ornamental tree, food, and medicine. In this study, we aimed to investigate the morphological characteristics including the leaves, flowers, buds, and fruits, and to compare these characteristics using a multivariate analysis between the three native Sorbus spp. in Korea and one introduced species (S. aucuparia). From the principal component analysis (PCA) of 28 characteristics, three principal components were obtained, which explained the variation of inter-specific relations among the genus Sorbus. The first, the second and the third components contributed 58.95, 29.79, 11.26% of the variations, respectively. The first principal component was related to ‘Fruit width’, ‘Length of a terminal leaflet’, ‘Petal length’ and ‘Winter bud width’. The second principal component was related to ‘Number of the leaflet’, ‘Number of the fruit per fruiting laterals’, ‘Length of a upper rachis’. And the third principal component was related to the ‘Diameter of a rachis’ and ‘Winter bud length’. According to the cluster analysis based on 28 characteristics, the Sorbus spp. were classified into two groups with an average distance greater than 7.0 between the group. S. amurensis and S. aucuparia was in group I, and sambucifolia and S. commixta was in group II.