This study presents the results of investigations concerning variations in traits that effect structure of biomass yield in eight selected clones of common osier (Salix viminalis L.) from the willow collection at the University of Warmia and Mazury in Olsztyn. Additionally, analysis of clone/genotype interactions with years was performed for these traits. The study was conducted on two clones from the oldest Polish forms of common osier, namely, Paskowka and Gigantea. Three newer collected Polish common osier clones, and three clones from Swedish cultivars of common osier, were also used in this study. Early development stages of willow plants were investigated in field experiments. The study began with the planting of the willows and ended with harvesting after the third year of growth. The experiment was performed in the random block design in three replications. Analysis of variance on the tested clones of common osier with terms of their yield structure traits was performed on plant height, tillering, shoot diameter and yield. The analysis showed that a significant variation between clones begins in the second year of growth. Moreover, a significant genotype and environment interaction was found for all the willow clones, in terms of yield, which is expressed by the weight of one plant. However, this interaction for other traits was significant only in relation to certain clones. In the third year of cultivation old Polish willow clones in comparison with the Swedish and new Polish clones have higher plant weight (yield), tillering and shoot diameter. 2010 Elsevier Ltd. All rights reserved.