Abstract A five-year-old planting is described which includes two triploid quaking aspen ( Populus tremuloides Michx.) clones, two triploid hybrid families ( P. tremuloides × P. tremula ) and two families of diploid quaking aspen. Significant differences between types of materials in specific gravity,height and diameter growth, natural pruning number of branches, branch angle, stem straightness, and branch length were found. Simple correlations between specific gravity and growth emphasize the lack of an adverse influence of rapid growth on specific gravity.