Seed Dispersal

1. Seed Dispersal

2. flower pollinated by animals Reproduction in plants — getting the flowers pollinated • Plants have adaptations to help them in pollination. • Flowers that are pollinated by animals are usually large and colourful. • They also have nectar and a fragrance so that the animals are attracted to them.

3. flower pollinated by wind Reproduction in plants — getting the flowers pollinated • Plants have adaptations to help them in pollination. • Flowers that are pollinated by wind are usually small, plain and without fragrance because they do not need to attract animals.

4. From Flower to Fruit • When all the ovules in a flower have been fertilized, the petals, stamens, stigma and style are no longer needed. • They will usually wither and fall, leaving an ovary in which the ovules are developing into seeds. • The fruit protects the seeds. • What is so important about seeds such that they need protection? Mrs Theresa Teo GE2003 Edited Mr Lin Lixun GE2009

5. Flower to Fruit Mrs Theresa Teo GE2003 Edited Mr Lin Lixun GE2009

6. Pea fruit from flowers Mrs Theresa Teo GE2003 Edited Mr Lin Lixun GEO2009

7. The Fruit and the Seeds • Seeds will grow into new plants and ensure the continual existence of that type of plant. • However, seeds cannot grow too close to their parent plant. Why? • OVERCROWDING • Overcrowding leads to competition for: • Water • Space • Nutrients • Light • Get to grow in new habitats where conditions may be even better. Mrs Theresa Teo GE2003 Edited Mr Lin Lixun GEO2009

8. Before we look at dispersal… • Take note of the THREE points: • Dispersal method of the fruit and the dispersal agent. • Characteristics of the fruit that supports dispersal. • Dispersal pattern of the fruit. Mrs Theresa Teo GE2003 Edited Mr Lin Lixun GEO2009

9. AGENTS OF DISPERSAL • Seeds and fruits are modified in different ways to be dispersed using one or two of the agents of dispersal. • Which parts get modified? The testa and pericarp are often modified to help in dispersal Seed An ovule which has been fertilised and become mature. Its wall is the testa. A mature ovary which contains fertilised seeds. Its wall is the pericarp Fruit Mrs Theresa Teo GE2003 Edited Mr Lin Lixun GEO2009

10. Reproduction in plants — getting the seeds dispersed • Flowering plants have different adaptations to enable their seeds to be dispersed as far away as possible. • The different methods of seed dispersal are… • by wind • by animals • by water • by splitting open forcefully

11. Reproduction in plants — getting the seeds dispersed What are the adaptations that help thesefruits/seeds to be dispersed? • Dispersal by wind • small • light • dry • wing-like shorea angsana

12. Dispersal by Wind • Plants which depend on the wind for the dispersal of seeds usually have • light seeds or • wings or • a parachute of fine hairs or • feathery hairs that act like many little parachutes • to help keep them floating in the air Mrs Theresa Teo GE2003 Edited Mr Lin Lixun GEO2009

13. Dispersal Pattern - Wind Parent Wind direction Legend Offspring

14. How about lovegrass? How does it disperse? Reproduction in plants — getting the seeds dispersed What are the adaptations that help thesefruits/seeds to be dispersed? • Dispersal by animals (eaten) • bright colours • sweet • juicy • Dispersal by animals (carried) • small • hooks stiff hairs tomato

15. Dispersal by Animals • Three ways • First way • The seeds or fruits have hooks or sticky hair that catch onto the fur of animals or clothing of human beings • Second way • Fruits get eaten by animals and seeds are thrown onto the ground as they are too big to be eaten by animals; or • Fruits and seeds get eaten by animals but the seeds are too hard to be digested by animals and are passed out in the droppings • Third way • Animals collect the fruits and seeds and take them to their burrows. Mrs Theresa Teo GE2003 Edited Mr Lin Lixun GEO2009

16. Dispersal Pattern - Animals Parent Wind direction Legend Offspring

17. Reproduction in plants ― getting the seeds dispersed What are the adaptations that help thesefruits/seeds to be dispersed? • Dispersal by water • buoyant • waterproof • air spaces • Dispersal by splitting open • dry and hard fruit wall coconut saga

18. Dispersal by Water • Plants which depend on the water for the dispersal of seeds usually have • Some feature that will allow it to float • Some protective covering to protect it during its long water journey. Mrs Theresa Teo GE2003 Edited Mr Lin Lixun GEO2009

19. Pong Pong Coconut Mrs Theresa Teo GE2003 Edited Mr Lin Lixun GEO2009

20. Nipah Fruit Lotus Fruit Pod Mrs Theresa Teo GE2003 Edited Mr Lin Lixun GEO2009

21. Dispersal Pattern - Water Parent Downstream Wind direction Legend Offspring

22. Dispersal by Explosive Mechanism or Splitting of the Fruit The fruit wall suddenly breaks into several parts and the movement causes the seeds to be shot out. This is caused by the unequal drying up of the fruit wall. The wall may split in one, two or many places along the line/lines of dehiscence (lines of splitting). Mrs Theresa Teo GE2003 Edited Mr Lin Lixun GEO2009

23. Mrs Theresa Teo GE2003 Edited Mr Lin Lixun GEO2009

24. Unripe Ripe Mrs Theresa Teo GE2003 Edited Mr Lin Lixun GEO2009

25. Ripe and unripe Kapok fruits Mrs Theresa Teo GE2003 Edited Mr Lin Lixun GEO2009

26. Mrs Theresa Teo GE2003 Edited Mr Lin Lixun GEO2009

27. Dispersal Pattern – Splitting Action or Explosive Mechanism Only Parent Wind direction Legend Offspring

28. Dispersal Pattern – Splitting Action WITH Wind Parent Wind direction Legend Offspring

29. seed dispersal by wind by water by animals by splitting open • Fruits/seeds • dry and hard fruit wall • Fruits/seeds • small • light • dry • wing-like • Fruits/seeds • buoyant • waterproof • air spaces • Fruits/seeds • brightly coloured • sweet • juicy • Fruits/seeds • small • hooks • stiff hairs At a glance… Adaptations for reproduction plants