This study presents the results of investigations of variation, genotype x year interactions and genotype x year x location interactions for the yield and morphological traits of several selected clones of energy grasses of the genus Miscanthus. The analyses were performed on the best clones of selected hybrid plants, which were obtained within the species M. sinensis or are the result of interspecific hybridization of M. sinensis and M. sacchariflorus. Analyses were conducted on the basis of three-year field trials at two locations. The young plants produced from in vitro cultures were planted at a density of one plant per m(2). The early stages of plant development, from planting until peak yield in the third year of cultivation, were analysed. Statistical analyses performed on the yield and morphological traits as well as changes in these characteristics over the successive years of the study showed considerable genotypic variation for traits under study. Moreover, significant genotype x year interactions as well as genotype x year x location interactions were observed in terms of yield and morphological traits. Based on the collective results of the study, we suggest that apart from M. x giganteus particularly hybrids of M. sinensis x M. sacchariflorus, should be taken into consideration in genetic and breeding studies on the improvement of yield from energy grasses of the genus Miscanthus. (C) 2010 Elsevier Ltd. All rights reserved.