The guys over at the Smithsonian Channel run a great show about plants. One of the recent short videos they posted online show how violets, touch me nots, and squirting cucumbers employ an impressive ballistic seed dispersal mechanism.
In the case of violets, the explosive mechanism of the pods relies on turgor pressure (specialized plant cells absorbing water until their membrane collapses) to provide the bang needed to launch a new generation of seeds to life.
Another mechanism that plants use is called dehiscence, the splitting at maturity along a built-in line of weakness in a plant structure in order to release its contents.