Morphological characteristics for classifying evergreen azalea (Ericaceae) cultivars in China using numerical taxonomy

摘要

Azaleas are among the 10 famous traditional flowers in China having a long cultivation history since the Tang Dynasty. Today, there are probably over 300 evergreen azalea cultivars preserved in different nurseries, all of which are usually classified as belonging to East, West, Summer and Hairy groups. Numerical taxonomy was carried out to determine the phenetic relationships between cultivars. Sixty six evergreen azaleas cultivars were studied based on 30 morphological characters (13 qualitative and 17 quantitative). Cluster analysis using unweighted pair group method with arithmetic average (UPGMA) and principal coordinate analysis (PCO) was performed by using NTSYS software. Mantel's test showed a good fitness between the cluster analysis and Euclidean distance matrix. The first three axes in PCO explained 49.94% of the total variation, and revealed that 14 characters, most of which are related to flowers, played an important role in numerical taxonomy. Both cluster analysis and PCO suggested that cultivars in the East and summer groups were distinct from other groups in the 4 group classification system based on the morphological characteristics, but the West and Hairy groups were closer when concerned primarily with phenetic relationships.