Plant nutation relies on steady propagation of spatially asymmetric growth pattern

Nutation is one of the most striking and ubiquitous examples of the rhythmic nature of plant development. Although the consensus is that this wide oscillatory motion is driven by growth, its internal mechanisms remain to be fully elucidated. In this work, we study the specific case of nutation in compound leaves of the Averrhoa carambola plant. We quantify the macroscopic growth kinematics with time lapse imaging, image analysis and modelling. Our results highlight a distinct spatial region along the rachis-situated between the growth and mature zones-where the differential growth driving nutation is localised. This region coincides with the basal edge of the growth zone, where the average growth rate drops. We further show that this specific spatiotemporal growth pattern implies localised contraction events within the plant tissue.