A look at the squirting cucumber’s explosive seed dispersal in both real time and in slow motion. Credit: Helen Gorges/CC BY-NC-ND
Ballistics is not usually linked to botany, yet the squirting cucumber’s unique method of seed dispersal draws interest from scientists. Known for its ability to explosively release seeds, this fascinating plant has become the focus of high-speed video research both in natural settings and controlled environments. Graduate student Helen Gorges from Kiel University’s Zoological Institute presented her findings at the Society for Experimental Biology Annual Conference in Antwerp, Belgium.
Commonly referred to as “noli me tangere” or “touch me not,” the squirting cucumber (Ecballium elaterium) may be viewed as a weed or invasive species in some areas, while in others, it is appreciated for its ornamental value. It’s worth mentioning that the fruit’s extract serves as a potent laxative; if ingested or inhaled, it can have toxic effects, including serious conditions affecting the nasal mucosa. Upon ripening, the fruit can eject a stream of mucus-like fluid containing seeds at high velocity, showcasing a remarkable instance of rapid plant movement.
As glucosides accumulate in the sap of the fruit, pressure builds internally, causing the fruit to detach from its stalk. This leads to a rapid contraction of the pericarp, violently ejecting both the fruit and the seeds through a small opening. The squirting mechanism is further enhanced by physical changes in the fruit as it dries out, causing its cells to coil, bend, or twist due to (hygroscopic movement).
A slow-motion view (over 300 times slowed) of the squirting cucumber’s seed dispersal. Credit: Helen Gorges/CC BY-NC-ND
Interestingly, a study from 2019 found that this method of seed dispersal is not the most efficient. This finding has positive implications for almond growers, as it allows farmers to strategically apply herbicides in areas most affected by the squirting cucumber. Additionally, the force behind the ballistic dispersal can cause the plant tissue to fracture. Gorges explained that “numerous factors must align perfectly to disperse the seeds efficiently without compromising the plant’s integrity prematurely,” prompting her investigation into the biomechanics governing the fruit’s maturation and readiness for seed dispersal.
