Abstract:Responses to mechanical stress (such as wind) should be suppressed in dense vegetation since the resultant shorter stature would lead to low fitness. However, this point has been debated, i.e. it has been argued that in dense vegetations a sensitivity to mechanical stress might provide an additional cue to shade avoidance. For 10 different genotypes of the clonal plant Potentilla reptans, the effects of shade (15% of daylight with a red: far red ratio, R/FR of 0.3 vs. 50% daylight and R/FR of 1.2) and wind (0 or 40 daily brushes with a duster) on the mother leaf properties were investigated. All genotypes exhibited typical “shade avoidance” responses under shade, such as the production of fewer leaves with longer petioles, reductions in petiole diameter, and the production of more rigid petiole tissue (petioles with a higher Young′ modulus). Wind-treated plants produced more leaves with shorter and thicker petioles made of more flexible tissue (lower Young′s modulus). All responses to wind are different from responses to shade. Interestingly the responses to wind in leaf of Potentilla reptans were opposite in nature to the responses to light.