METHODS OF FRUIT AND SEED DISPERSAL
- Fleshy fruits are eaten by animals.
- Animals are attracted to the fruits by the bright colour, scent or the fact that it is edible.
- The seeds pass through the digestive tract undamaged and are passed out with faeces. E.g. tomatoes and guavas.
- Such seeds have hard, resistant seed coats.
- Others have fruits with hooks or spines that stick on animal fur or on clothes.
- Later the seeds are brushed of or fall off on their own e.g. Bidens pilosa (Black jack).
- Fruits and seeds are small and light in order to be carried by air currents.
- A fruit that is a capsule e.g. tobacco split or has pores at the top e.g. Mexican poppy.
- The capsule is attached to along stalk when swayed by wind the seeds are released and scattered.
- Some seeds have hairy or feather-like structures which increase their surface area so that they can be blown off by the wind e.g. Sonchus.
- Others have wing-like structures e.g. Jacaranda and Nandi Flame.
- These extensions increase the surface area of fruits and seeds such that they are carried by the wind.
- Fruits like coconut have fibrous mescocarp which is spongy to trap air, the trapped air make the fruit light and buoyant to float on water.
- Plants like water lily produce seeds whose seed coats trap air bubbles.
- The air bubbles make the seeds float on water and are carried away.
- The pericarp and seed coat are waterproof.
Self dispersal (explosive) Mechanism
- This is seen in pods like bean and pea.
- Pressure inside the pod forces it to open along lines of weakness throwing seeds away from parent plant.