Dispersal by explosion

In some plants the pericarp of the fruit bursts, and the seeds are dispersed far away.

The causes of the bursting are touch, becoming wet, or dry environmental conditions.

Examples — rubber, madatiya, okra, kudalu.

Figure to be added

Figure 14.18 — fruits and seeds dispersed by explosion: rubber, madatiya and okra, each with the pericarp split open.

The plant supplies the energy itself

This is the one method that hires no agent. The pericarp dries unevenly and builds up tension in its own wall, like a stretched spring; when it finally splits, that stored energy throws the seeds several metres. The plant paid for the throw when it built the fruit.

Three triggers, one mechanism

Touch, wetting and drying are not three different mechanisms — they are three ways of releasing the same built-up tension. Which trigger a plant uses decides when the seeds fly, and drying is the commonest because a dry day is a good day to be thrown a long way.