Abstract:In order to reveal the phenotypic diversity of different Elymus germplasm,we investigated twenty-two phenotypic traits of thirty-eight populations from eight provinces.Phenotypic variation between and within the populations of Elymus was analyzed by the coefficient of variation and diversity index analysis methods,and the pattern of variation morphological traits and geographical factors were analyzed by correlation analysis.The thirty-eight populations of Elymus were classified by using cluster analysis.The results showed that:(1)The variation coefficients of height from flag leaf to basal spikelet（44.695%）in vegetative organs and spikelet number per panicle（77.005%） in vegetative and reproductive was the hightest,respectively.(2)The overall mean phenotypic diversity index among different species(E.excelsus,E.cylindricus,E.tangutorum and E.sibiricus) was 1.333,ranging from a high of 1.560 in E.dahuricus to 0.920 in E.cylindricus.(3)According to correlation analysis,the elevation,longitude and annual mean temperature have remarkable influence on phenotypic characters.(4)Cluster analysis by twenty-two phenotypic traits showed that the thirty-eight populations of Elymus were divided into four groups.The phenotypic traits are not in the same group by the near geographical distances with cluster analysis.The Elymus germplasm had rich morphological diversity.And they were relevant to habitants.Population integrity is the key determining factor for protection of germplasm resources of Elymus during the collection.