Some plants distribute their seeds by violently ejecting them so that they
fall well away from the parent plant. This is explosive dispersal. An example of this is
plants which belong to the Pea Family (Leguminosae). They produce seed pods which dry in
the sun.
As a pod dries, tensions are set up in the wall of the pod eventually
causing it to split along two lines of weakness. As the two halves curl back, suddenly
released like a tense spring, they flick out the seeds inside in an explosive manner. In
the picture opposite, the halves of a seed pod which has ruptured in this way are clearly
twisted, in contrast to the whole pod which is entire.
Gorse is a good example of this. Sitting near Gorse
bushes on a hot day in summer in Britain, can be like sitting near a firing range, as the
exploding pods sound almost like gun shots. The small seeds are very effectively thrown
away from the immediate area.