Population sampling
We have conducted field investigations of Cerasus serrulataaccording to specimen and literature records since 2010, and a total of 18 populations of Cerasus serrulata with 327 accessions have been collected (Table 1, Figure 1). Among them, seventeen populations were from China and one was from Korea. Green, young and healthy leaves were gathered from individuals at least 30 m apart, and were quickly stored in silica gel. All accessions were used for cpDNA analysis, while 174 were used for ITS analysis, with a maximum accession number of 10 for each population (Table 1 ). The whole collections should have covered the most of the distributions of Cerasus serrulata .