Scientists from the University of Manchester have uncovered the secrets behind one of nature's quirkiest plants - the squirting cucumber.
While most plants rely on external forces such as animals, wind, or water to spread their seeds, this cucumber - scientifically known as Ecballium elaterium - launches them at high speed in a pressurised jet, sending seeds over 10 metres from the parent plant.
The fruit has long intrigued scientists for its dramatic seed dispersal method, but the exact mechanism and its benefits were poorly understood.
The new research, published in the journal PNAS, uses high-speed videography, image analysis, lab experiments and mathematical modelling to examine each phase of the ejection process.
They found that as the cucumber ripens, fluid from the fruit is squeezed into the stem, causing it to stiffen and straighten, and changing the inclination of the fruit so that it is better suited for launching seeds over long distances. The internal pressure in the fruit is so high that, once it detaches from the stem, the fluid and seeds within the shell are explosively launched in a powerful jet.
The finding has important implications for understanding the plant's population dynamics and offers insights into evolutionary adaptations related to explosive fruit mechanisms. Its seed dispersal strategy could also inspire new technologies.
Lead researcher Finn Box from The University of Manchester, said: "Seed dispersal is incredibly important for plant survival and population, and we see a wide range of dispersal strategies across the plant kingdom, each adapted to different ecological needs.
"This research is the first comprehensive mechanical explanation for how the cucumber plant launches its seeds with remarkable speed and precision - a process almost unheard of in the plant world.
"The explosive launch of the cucumber plant has evolved over generations to help it survive. The way that the stem is able to re-position itself to the perfect angle and build enough pressure to maximise spread has been key to help regulate the plant's population. These mechanisms allow the plant to disperse seeds over a wide area and reduce overcrowding and competition among offspring and other neighbouring plants, ensuring a better chance of survival for the next generation."
The research could also help scientists better understand how plants might adapt to environmental changes such as temperature, rainfall patterns and soil conditions due to climate change. Effective seed dispersal plays a critical role in this adaptation as it allows them to move on and colonise new, more stable environments.
It is also thought that understanding the mechanics of explosive seed dispersal could inspire new technologies, such as smart medical devices that can eject drugs on demand and thereby increase the concentration of medication at target sites within the body.
