| Palmae is a very distinguished colony in the monocotyledon and a very important component of the tropical flora. It is one of the three most important economic families in the world. Palms are widely regarded as being second only to the grasses in economic importance and whole communities in the tropics and subtropics may depend on palms for their livelihood. Besides this, they are widely cherished and used in modern life and urban greening around the world due to their rich species, widely habitat fitness and unique ornamental values. This has also happened in Xiamen and other cities in southern China. But in fact, difficulty in classification has been an obstacle in the utilization, conservation and application of the palm resources for the specialty of their geological distributions and morphological structures, and the lack of research on the physio-ecological principles in cultivation and appliance with the palm resources has not only coursed waste in plant introduction and acclimatization but also severely influenced the elaboration of the ecological efficiency of palms as an emblem of tropical plant landscape in the construction of urban green system.In this work, some species of Palmae cultivated in the Xiamen botanical garden had been selected to be analyzed their genetic diversity with RAPD (random amplified polymorphic DNA) technique. According to the result of genomic DNA amplified with PCR (polymerase chain reaction), genetic distance and similarity between different palm species werecalculated on Nei' s estimate of similarity and genetic distance. A primary but first time research at the phylogenetic relationships of some genera and species, the molecular classification and identification of some puzzling species of Palmae was carried out through UPGMA (unweighted pair group mean average) cluster analysis of the genetic distance together with comparative study of the morphological structure characteristics. The shade tolerance and caloric ecology of some palm species were also studied. No former research reports on palms in these areas have been issued by now. Results and conclusion of the work turned out like following:1. Among the three methods used in the experiment of DNA extraction, only CTAB, adding PVP in the DNA isolation step, had effectively reduced the disturbance from fiber or other plastids and extracted suitable genomic DNA as template for RAPD process. PCR amplifications were performed in a final volume of 25 mm3 containing 0. 5 units Taq Polymerase, 2. 5 mm3 dNTPs(lmmol/dm3) , 2 mm3 primer (5umol/dm3), 2 mm3 MgCl2(2 mmol/dm3), 10 mM Tris-HCl, and 20 ng template DNA. The reaction system was covered with 20 mm3 paraff ine. Forty cycles ( including denaturation 1 min at 94"C, annealing 1 min at 36℃, elongation 2min at 72℃) were followed by a final elongation step of 7 min at 72℃. Amplification was performed in a T3 PCR thermocycler. The amplification resulted with abundant polymorphic bands, better stability and repeatability.2. Genetic diversity of 12 species in Rhapis, Chuniophoenix and Trachycarpus was analyzed with RAPD molecular marker technique. 13effective primers from 29 arbitrary 10-oligonucleotide primers were used and amplified 837 DNA bands from the 12 samples, of which 657 bands were polymorphic RAPD loci, covering 78.49% of the total. UPGMA cluster analysis on the RAPD bands and comparative study on their morphological structure demonstrated that 1), the average genetic distance between 8species of Rhapis be 0. 45, they shared a high genetic similarity and small difference in morphology; 2), the genetic distance between Rhapis humilis and R. humilis cv. was only 0.24, while the distance between R. excelsa and R. sp. (usually treated as R. excelsa var. vastifolius) reached 0.44. The later pair could be treated as two different species based on the DNA molecular taxonomic analysis; 3), genetic distance between the two species of Phoenix, which were very similar in appearance and easily confused in horticulture and appliance, was 0.33, differ...
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