Botanical Nerd Word: Ballistic dispersal

Impatiens capensis pod before and after explosion

Ballistic dispersal: (syn. ballochory) Mode of dispersal by which the diaspores are actively or passively catapulted away from the plant. This can either happen arbitrarily or be set off by an external trigger.*

Plants in the genus Impatiens use ballistic dispersal to spread their seeds. This is where Impatiens capensis got the common name ‘touch-me-not.’ When you touch the ripe seed pods of this plant, their internal tensions cause them to burst open, flinging seeds all around. The image shows the pod before and after seed release.

*Kesseler, R. & Stuppy, W. (2006). Seeds: Time capsules of life. Buffalo: Firefly Books.