In woody species, wood provides many functions such as nutrient transport, organic compounds storage and a mechanical support. Furthermore in human society, the wood is a source of raw material (paper industry), materials (construction, decoration ...) and energy. It seems now important to have a better control over wood production and quality and to gain a better understanding of how mechanical constraints modulate secondary growth and wood differentiation. In response to environmental stress, the plants acclimate and adjust their growth accordingly. External mechanical loadings, such as wind, lead to a decrease of primary growth, an increase of secondary growth, and modifications of stem mechanical properties and biomass reallocation to roots. Recent results showed that mechanical signals generate wood differentiation adjustments leading to the production of a wood presenting similarities with tension wood: the Flexure Wood. Here we present an analysis of the morphological and anatomical consequences of repeated bending on young poplar stems with a special emphasis on the effects of the uneven spatial distribution of physical factors over the stem cross-section. Stem anatomical observations revealed that recurrent bending stimuli modify cambial activity both quantitatively and qualitatively. Wood differentiation appears to be modulated according to the sign of mechanical strain (tension or compression). Genes responsible for such responses, among which a gene encoding a CLE-type peptide, are under investigation.