Caution: This Cucumber Propels Its Seeds Catapult-style

A Master of Seed Artillery: The Squirting Cucumber's Unique Dispersal Method

Scientists have been investigating the extraordinary seed-launching capabilities of a peculiar cucumber species.

A few years back, a biomechanist at Kiel University came back to Germany from a trip to Turkey with an unusual gift for a doctoral student.

"He excitedly handed me a bunch of cucumbers with a warning: 'They might explode – could be an interesting project for you,'" she explained.

These weren’t your typical grocery store cucumbers. They were their smaller, hairier, and toxic relatives known for their explosive nature.

Though lacking in taste appeal, this cucumber variant compensates with a powerful seed-throwing mechanism. Ripe and full of pressurized liquid, these cucumbers are primed to burst at the slightest touch, scattering seeds over considerable distances to minimize competition from the parent plant.

Learning about this natural marvel fascinated Gorges. "Our curiosity was piqued: How exactly does this explosive mechanism operate?" she shared.

Together with her team, Gorges delved deeper into this botanical marvel, presenting their findings at a recent Belgium conference and in an upcoming scientific journal. "This botanical curiosity ensures its next generation spreads far and wide," Gorges happily concluded.

Understanding the Optimal Launch Trajectory

To decode the mechanism, Gorges and her team photographed numerous cucumber specimens from both Turkey and a local botanical garden in Germany, focusing on the angle between the fruit and stem once the fruit is ripe.

They discovered that the angle was consistently over 50 degrees. "This angle is crucial," she explained, "as it maximizes distance with air resistance factored in, ensuring an ideal parabola for seed projection."

Upon further examination, they discovered around fifty seeds packed within the cucumber waiting to be catapulted. Using micro-CT scans, they captured the seeds’ orderly arrangement, ready to launch, directionally aligned.

High-speed cameras were employed to capture the seeds’ ejection events in slow motion.

Playback of these recordings showed the stem lifting and a liquid jetting out, propelling the seeds one by one. The seeds could attain speeds nearing 30 miles per hour, reaching distances up to nearly 40 feet.

This coincides with research from a 2024 English study, estimating launch angles near 43 degrees, velocities of 37 miles per hour, and comparable launch distances.

According to a Pomona College physicist unlinked to these studies, "Propelling a small object such a distance is no easy feat. This plant is among the rare few, if not the only one, utilizing pressurized liquid for seed ejection — boosting seed acceleration on release."

The Magic of Adhesive Seeds

Gorges also studied the seed’s sticky coating.

She tested its hold by letting the seeds dry on glass slides, finding their adhesive strength sufficient to bear up to a six-pound load.

According to a Duke University biologist, though uninvolved in the study, "The impressive launch speed might primarily serve to ensure seeds adhere upon impact, potentially facilitating their spread via larger carriers."

Future experiments might explore how effectively seeds stick to different kinds of surfaces at varying speeds.

Patek believes that the insights gained from these cucumbers might lend themselves to various innovations. "These natural adhesives and launching techniques might find modern applications," she mused, highlighting potential uses in agriculture or clinical dosing.

Such seeds, with adhesion properties altered by environmental moisture, could inspire new materials for different conditions.

Indeed, not too shabby for a seemingly innocuous plant!