In some cases, seeds do not enter their final stage of development, which is maturation drying. These seeds germinate in the fruit while they are still on the plant. In crop plants, this is undesirable because the seed can not be collected for food processing or seed production.
Vivipary is considered a genetic mutation, but the occurrence of vivipary is often dependent on environment and is observed more often after wet weather.
For a few species, vivipary is the normal type of seed and seedling development. Mangrove (Rhizophora mangle) is a type of plant that grows along the edge of waterways.
In mangrove, the seed germinates while still on the plant.
The long radicle (arrow) emerges from the fruit to form a javelin-shaped structure that eventually falls off the plant and sticks the seedling into the soft wet soil around the plant.