Robust posture control by plants in dynamic gravity field

Plants are known for their remarkable adaptability to environmental stimuli. For instance, it is well-known that a tilted plant will eventually straighten vertically, demonstrating the influence of an external stimulus, gravity, but also an internal stimulus, known as proprioception, the sensing of the plant's own shape. Using a morphoelastic rod model, we show that these effects can be modulated when a potted plant is additionally rotated along the plant's axis, as in a rotating clinostat, a classic experimental instrument, leading to intricate shapes. In the absence of rotation, we identify a universal planar shape towards which all shoots eventually converge. With rotation, we demonstrate the existence of a stable family of three-dimensional dynamic equilibria where the plant axis is fixed in space. Further, the addition of axial growth leads to further steady behaviors, such as solitary waves. Overall, this study offers new insight into the complex out-of-equilibrium dynamics of a plant in three dimensions and further establishes that internal stimuli in plants are key for robust posture control.