Shear waves in plant leaves at ultrasonic frequencies: Shear properties of vegetal tissues

Shear Waves are observed in leaves of some plant species (Epipremnum aureum and Vitis vinifera) using air-coupled ultrasound, through transmission and oblique incidence. Shear waves appear as a modification of the thickness resonance pattern of the longitudinal wave measured at normal incidence. Poisson's ratio, shear wave velocity and attenuation coefficient of shear waves in the leaves are extracted from the measured resonance spectra using a bilayer acoustic model for the leaves. Influence of water content or the degree of leaf development on shear wave properties is also analyzed.