A General 3D Model for the Dynamics of Rod-Like Sensory-Growth Systems and their Mechanical Interaction with the Environment*

Plant shoots and roots capitalize on their slender structures to successfully negotiate unstructured environments while employing a combination of two classes of growth-driven movements: tropic responses, growing toward or away from an external stimulus, and inherent nastic movements, such as periodic circumnutations, which promote exploration.
During growth, organs often encounter various mechanical obstacles, such as soil, stones, or other organisms. Forces exerted by the organs on such obstacles, originating from growth processes, subsequently induce mechanical stresses on the organs themselves, yielding a rich and complex dynamics.
In order to emulate these dynamics in a 3D environment, we recently developed a general model for the growth of rod-like organs, adopting the Cosserat rod model. The dynamics are based on the combination of active growth-driven movements and passive elastic interactions with external objects or fields.
This model, together with its robust numerical framework, provides a powerful tool to deepen our understanding of how rod-like sensory-growth systems, such as plants, fungi and neurons, interact with their environments through a combination of both active and passive responses.