Abstract
Robots play an ever-expanding role in society by performing a broad range of tasks. However, there are growing concerns about their environmental sustainability, as many conventional robotic systems rely on materials that are neither renewable nor degradable. Consequently, significant efforts are being made to develop eco-friendly robots built from sustainable and biodegradable materials. In this context, plants represent a promising direction, as the biomaterials composing plants are biodegradable, and their inherent multifunctionality as living organisms, including sensing, actuation, energy harvesting, and self-healing, makes them strong candidates for realizing biodegradable robotic systems. Moreover, they are abundant and renewable resources. Recent studies have demonstrated plant-based robotic systems that harness some of these features, helping to establish plant robotics as an emerging research field. Among the many functions plants offer, actuation is pivotal, as it enables physical robotic motion, such as locomotion and grasping, which substantially broadens the potential applications of plant robots. Focusing on plant movement, this article reviews key plant species and their behaviors through the perspective of actuation characteristics. It also examines the current landscape of plant-based robotic systems and outlines future research directions in this rapidly growing field.