Ecballium

Ecballium is a genus of flowering plants in the family Cucurbitaceae containing a single species, Ecballium elaterium, also called the squirting cucumber or exploding cucumber (not the same plant as Cyclanthera brachystachya). Its unusual common name derives from the ripe fruit squirting a stream of mucilaginous liquid containing its seeds as a means of seed dispersal, an example of rapid plant movement. E. elaterium is native to Europe, northern Africa, and temperate areas of Asia, and is considered an invasive species. It is grown as an ornamental plant elsewhere, and in some places it has naturalized. The tissue in the fruit of the Ecballium elaterium that surrounds the seeds is thin walled, facilitating the propulsive release of seeds by "squirting". Pressure to expel the seeds is created by the increased concentration of glucoside and elaterinidin in low volumes of cytoplasm, leading to an osmotic pressure of up to 27 atms. The pressure-building method may depend on the Phloem sieve tubes, indicating that the squirting mechanism can be decreased in water stressed conditions. The fruit also uses hygroscopic movement and stored elastic energy to squirt the seeds out of the fruit. This method is done passively where the fruit changes its structure as it dehydrates and deteriorates, causing movement. This movement may be due to coiling, bending, or twisting cells to change its morphological shape as the cells dry. Because drying cells are mostly made up of cell wall, the shape is determined by the cell wall, providing a method for catapulting of seeds to eject them out of the plant. Sudden movements in plant tissues are prone to different types of mechanical instabilities. In the case of E. elaterium, due to the relationship between the duration of movement and the size of the tissue, the plant tissue fractures. Effectiveness of the dispersal seems to be low as a study found that even though the E. elaterium could have sprayed its seed to the whole plot, the size and location of the infested areas remained relatively similar.