​​Why some part of Plant explode upon touching?

Plants use many strategies to disperse their seeds, but among the most fascinating are exploding seed pods. Violets, poisonous squirting cucumbers, and touch-me-nots or Impatiens capensis (not to be confused with these touch-me-nots) have an effective way of dispersing their seeds: They burst! The forceful ejection sends the seeds flying as far away as possible from the original plant. Several teams of scientists spanning different disciplines and countries, including Oxford mathematicians Alain Goriely and Derek Moulton, along with colleagues from Oxford’s departments of Plant Sciences, Zoology and Engineering, worked together to discover how the seed pods of popping cress explode. A rapid movement like this is rare among plants: since plants do not have muscles, most movements in the plant kingdom are extremely slow. However, the explosive shatter of popping cress pods is so fast — an acceleration from 0 to 10 metres per second in about half a millisecond — that advanced high-speed cameras are required to see it. The scientists, led by Angela Hay, a plant geneticist at the Max Planck Institute for Plant Breeding Research, discovered that the secret to explosive acceleration in popping cress is the evolutionary innovation of a fruit wall that can store elastic energy through growth and expansion and can rapidly release this energy at the right stage of development.