How Does the Cucumber Jump?

Have you ever encountered a Squirting Cucumber? They are frankly a bit alarming. The merest touch will send the fruit exploding its seeds and unpleasant liquid for metres, and you'd better be out of the way. This plant in the photos was in the courtyard of Preuilly's little local museum.

But up until just recently, it wasn't fully understood how the plant achieved its explosive power. The explosion lasts just 30 milliseconds, and the seeds, travelling at 20 metres per second, could end up 10 metres away. Oxford based scientists have now filmed and measured, and discovered something unique. What they realised was that the fruits become highly pressurised, filling up with mucilage. Then, amazingly, some of the fluid transfers back out of the fruit and returns to the stem causing it to become longer, thicker and stiffer. Crucially this causes the fruit to rotate to the perfect angle for blastoff. Finally the stem recoils from the fruit, causing the seeds to eject. These discoveries have implications for precise control of rapid drug delivery in medicine.

Ecballium elaterium or Squirting Cucumber as it is usually known in English (Concombre sauteur in French) is a perennial, native to Southern Europe, appearing wherever there is sandy, stony or waste ground. The plant is a member of the Cucurbitaceae family, so is genuinely a cucumber. The fruits are poisonous and were used medicinally in the past (as so often with poisonous plants, the right dose is actually beneficial, but it needs administering with a skilled and knowledgeable hand – something that is largely lost to us now). Apparently, the fruit is so strong a purgative that just absorbing the liquid from the seed capsule through the skin can have an effect. The liquid is also extremely irritating to the skin.

Because of its very effective seed distribution system, it can very easily take over an area, and consequently, it is necessary every now and then for brave souls covered from head to toe in protective gear to remove as much as they can to keep it under control in gardens and public spaces.