| Common Crapemyrtle (Lagerstroemia indica L.), mainly distributing both in southern and southwestern China , is an important ornamental tree species blooming from summer to autumn in China. In order to bring unknown L. indica cultivars cultivated, it is crucial to investigate, collect, and study its germplasm resources first. Based upon morphological traits as well as result analyses by AFLP techniques, some L. indica cultivars were identified and their DNA fingerprints were established. The main results were as follows:1. According to the investigation, there are 18 species of the genus Lagerstroemia distributing in China. L. indica, L. limii and L. subcostata are widely distributed, and L. intermedia, L. fordii, L. limii and L. stenopetala are endemic to China. The investigation results also show that there are at least 48 L. indica cultivars in China, 15 of which had not been reported before. These 15 cultivars are: ' Fenrei Chuqiang ', ' Baidie Feiwu ', ' Cengyun Jixue ', ' Bai Mixiang ', ' Jiaohu Yinwei ', ' Chuizhi Bai ', ' Chuizhi Fen ',' Chuizhi Hong ',' Hongdie Feiwu ',' Erceng Zi',' Lanse Yaoji',' Chuizhi Zi',' Lanzi', ' Zhizhi Zi 'and ' Hongye Ziwei '. There are about 10,000 older-than-100-year L. indica plants in China, and most of them were found in Pixian County, Sichuan and Baokang County, Hubei. The author concluded, therefore, that these two counties must have been the most important native growing areas of L. indica in history.2. All the investigated L. indica cultivars were named according to their own characteristics. A key of these newly-named cultivars was also worked out for quick identification. Meanwhile, standards for the eminent germplasms and their characteristics were also brought forward in the study. In term of the standards mentioned above, 6 eminent L. indica germplasms were identified: aromatic flower, red leaf, weeping branch, large flower , androptalous and mosaic leaf features,. Five species of Lagerstroemia and 30 cultivars of L. indica were collected and cultivated in two gardens specially set up for conserving germplasms and cultivar resources of Lagerstroemia both in Jigongshan Mountain and the Yellow River Tourist Area, Henan.3. By using Msel-Pstl digest and 7 primers, a suitable silver-staining AFLP system for L. indica was developed. Clear- and high-resolution DNA fingerprints were obtained, which meant success in DNA extraction, restriction-ligase reaction, double amplification, and the staining techniques.4. The AFLP results show that the genetic relationships between dwarf cultivars are close. Among them, the relationship between ' Fenrun ' and ' Aisheng Chuizhi Fen ' is the closest. The results also suggested a close genetic relationship between ' Baidie Feiwu ' and ' Cengyun Jixue ', ' Hongdie Feiwu ' and ' Lanse Yaoji ', ' Zizhao Yinwei ' and ' Baiyun Yingxia ', respectively. All the above cultivars are genetically far away from ' Bai Mixiang '. Furthermore, natural hybrids of L. indica, L. limii and L. subcostata are identified by AFLP techniques.The objective of this study was to provide scientific bases for establishment of gene pool, selection and breeding of eminent cultivars, seeking and conservation of new cultivars, and for protection and usage of genetic resources and their relationships in L. indica. Besides, DNA fingerprints of L. indica could also be used for genetic mapping, marker-assisted selection and map-based cloning. Therefore, the results wound exert important effects on genetic improvement of L. indica at the molecular level.
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