The squirting cucumber (Ecballium elaterium) is a phenomenal ballistic missile, unique in the plant world. The tubby little fruit looks somewhat like a pickled cucumber hanging on a stalk and when ripe it suddenly explodes, shooting off into the air like a rocket and squirting out its seeds in a jet-propelled stream of high-pressure slimy fluid, reaching speeds of about 20 metres a second and distances of about 10 metres from its parent plant.
As the fruit ripens, juice builds up inside it, creating tremendous pressure. Then in the countdown to the launch, some of the fluid is transferred from the fruit to the stem and lengthens, thickens and stiffens the stalk and tilts the cucumber to about 45 degrees, the ideal angle to launch the fruit and spread its seeds.
Finally, at the moment of blast-off, the stem recoils and the fruit fires off, spinning like a rugby ball and shooting out its seeds over a wide area. The extraordinary explosion is an ingenious way for the squirting cucumber to spread its seeds far and wide, trying to avoid the seeds competing with each other and with their parent plant.
