The mechanical secrets of the squirting cucumber

Rapid movement is rare in the plant kingdom, but is a prerequisite for ballistic seed dispersal. A particularly dramatic example of rapid motion in plants is the squirting cucumber (Ecballium elaterium), which explosively launches its seeds via a high-pressure jet, attaining velocities of around 20 m/s. This dispersal mechanism is completely unique among cucumbers, and has intrigued scientists for centuries. In this talk, I present our work on understanding the mechanics of this fascinating phenomenon. Our approach combines experiments, high-speed videography, quantitative image analysis and a suite of mathematical models. In particular, we uncover key mechanical interactions between the plant’s fruit and stem both prior to and during seed ejection. Combining modeling elements, we quantify and simulate the ballistic trajectories of seeds, demonstrating how the plant manages to disperse seeds over distances greater than 2000 times their length and with a nearly uniform distribution of seeds away from the parent plant.