Autochory - Dispersal of Seeds
This mechanism of self-dispersal is based on forceful expulsion of the seed from the fruit because of desiccation or turgidity of the cells of the pericarp. In balsam, Impatiens spp., for example, the fruit is a cylindrical capsule formed by the, fusion of five carpels. The fruit wall comprises three regions of which the middle is made up of radially elongated cells with high turgor pressure. This zone is termed expansion zone. In the dry, ripe capsule the cells of the expansion zone are in a state of high tension. However, the inner portion of the pericarp consists of 2 or 3 layers of collenchyma which offer resistance. At this stage even a mild touch or jerk results in separation of the carpels at the base. The five carpels instantly curl inward throwing the seeds at a distance of about 2 meters.
In Arceuthobium sp, the fruit is a pseudo berry enclosing a single seed. The mesocarp is formed by viscin cells. When the fruit is detached from its stalk the cells of the viscid layer generate a high pressure and the pericarp contracts to hurl the seed out with great force.