A domestic research team has uncovered how violets flick their seeds out one by one. As the fruit pod dries and folds inward, force concentrates at specific spots, and the center of that force shifts to push the seeds out in sequence. The team said this principle could be used to design wound-closure devices and soft robots.
The Ministry of Science and ICT said on the 19th that a joint team led by Hyun You-bong, professor in the Department of Biological Sciences at Seoul National University, Kim Ho-young, professor in the Department of Mechanical Engineering at Seoul National University, and Jeong So-hyun, professor in the Department of Robotics and Mechatronics Engineering at DGIST, analyzed the structure of violet fruit pods and identified this seed-release mechanism. The findings were published the same day in the international journal Science.
Violets are common plants, but their way of dispersing seeds is quite unique. Many plants scatter their seeds in all directions at once when the fruit bursts. In contrast, the violet uses the force of its elongated, pouch-like fruit shell, or "pod," drying and curling inward to flick out the seeds one by one.
Simply applying a strong force is not enough to launch the seeds in order. The point where the force acts must move to match where each seed sits. In robotics, motors, sensors, and controllers are usually needed to create such motion. But the violet achieves this with no extra devices, relying only on the pod's shape and folding pattern.
The team focused on how the violet pod dries and folds sequentially like a zipper closing. They described this as a "zippering" motion. Within the pod are regions that induce folding and a thin membrane that delivers force directly to the seeds. When the pod folds, force gathers along this membrane at the location of a seed, and as that focal point moves forward, it pushes the seeds out in turn. It works much like pinching and snapping each seed from the front with a finger.
By comparing real violet samples with a bioinspired device and analyzing pod cross sections, the team found that the pod cross section is close to a semicircular shape that effectively concentrates force. As the shapes at both ends of the pod and the geometric conditions interlock, the force generated during folding does not disperse but focuses where the seeds are.
The team said this can be seen as an example of "physical intelligence." Physical intelligence refers to designs in which an object's form, materials, and motion perform functions without complex electronics or computation. It could be applied to bioinspired devices that must concentrate force at specific points while minimizing wires, batteries, and motors—such as wound-closure patches and tools that gently grasp or resect tissue.
"Violets have evolved pod structures that efficiently transmit force with minimal resources," the team said. "This will aid research in soft materials and biomedical engineering that achieves precise motion through design alone, without complex devices."
References
Science (2026), DOI: https://doi.org/10.1126/science.aed2953