Abstract: The classification and relationship among 35 samples of longan (Dimocarpus longan Lour. ) have been studied by RAPD (random amplified polymorphic DNA) and statistical cluster analysis. These results showed that it was unlikely possible that "Lizhiben" and "Lizhi kongyan" were hybrid progeny of longan and litchi ( Litchi chinensis Sonn. ) as what some people believe. The "Lizhiben", and "Nanhu Jiaohe" were highly mutant varieties. There were some variance among the "Jiaohe" wilted-nut longan cultivars. Different cuhivars given the same name, such as "Dongbf', "Honghezi" and some other cultivar, were also possible. It was concluded that longan cultivars which have been tested in this research could be classified into 6 groups. The first group, including 12 cultivars such as "Shuizhang", "Youtanben", "Wulongling" etc., which were the well known best cultivars appropriate for producing dry longan, was named as Shuizhang-Wulongling group. The second group, including 11 cultivars like "Chike", "Jiaoyan", "Fuyan", "Chushuben" etc., was named as Chike-Chushuben group. The Dongbi series cuhivars were named after their cultivars as the Dongbi group. The special cuhivars, "Lidongben", "Nanhu Jiaohe" and "Lizhiben" were named respectively as Lidongben group, Nanhu Jiaohe group, and Lizhiben group, because of their more characteristic DNA polymorphism tested in all respective cuhivars. The results indicate that the application of RAPD technique in the taxonomic study has gained some resolution which could not be obtained by morphological analysis and has provided available data for developing longan production and for breeding new longan cultivars.

Key words: Dimocarpus longan, Taxonomy, RAPD