3.1.3. Cluster analysis based on phenotypic traits
A cluster dendrogram of 112 accessions was created from 20 phenotypic traits obtained from PC analysis (Fig. 2). The 112 accessions were divided into seven major groups. The G1 group only contained two accessions of CY-256 and CY-257 from Hainan Province, characterized by no flower, no bulbil, and no stem wing but spiny and turning left. The leaves were nearly round, and the tubers were small and nearly round. The G2 group consisted of 29 accessions, and the main features were stem wings, purple-green stems, purple tuber flesh color or purple inner epidermis color, no flowers nor bulbils, and purple-green petiole. The G3 group included 13 accessions and was very similar to the G2 group. The biggest difference was that the tuber endodermis color was mostly beige, while the tuber flesh color was mostly white. The G4 group contained nine accessions. CY-206 and CY-209 belonged to D. fordii , while the rest of the accessions belonged to D. opposita . The G5 group was composed of 40 accessions. The typical characteristics were flowers, bulbils, dark-green leaf color, yellow-green vein, columnar-white tuber flesh color, and a variation of length-to -width leaf ratio ranging from 1.2 to 1.5. The G6 group contained 19 accessions characterized by no flowers, no bulbils, oval leaves, purple petioles, yellow-green veins, and brown tuber skin.