Pollination is the transfer of pollen grains from the anther to the stigma of a flower. It requires an external agent such as wind, water, animals or gravity. There are two types of pollination: self-pollination which occurs within the same flower, and cross-pollination which involves pollen transfer between different flowers. The shape and form of pollen is related to its method of pollination. Flowers can be complete with all floral organs present, or incomplete missing one or more organs. They can also be perfect with both male and female organs, or imperfect with only one type of organ. Methods like dichogamy ensure cross-pollination by separating the maturation of anthers

4. Definition:
The transfer of pollen grains from the antherto the stigma
of a flower.
Pollen grains are immobile.They
cannot reach the stigma by themselves.
An external agent is required for this.It
can be wind, water, animal, gravity or
growth contact.

5. Two types of
pollination
Self-
pollination
Cross-
pollination

6. The shape and form of pollen is related to its method
of pollination..

8. • Complete
– all floral organs present (sepals, petals, stamens, pistil)
• Incomplete
– flower lacks 1 or more of the 4 organs

9. • Perfect - has both stamen (male organs) and pistil (female
organ)
• Imperfect - having only one type of organ
– Staminate - male organ present
– Pistillate - female organ present

10. imperfect
perfect
imperfect

11. (Hibiscus sp.) (Catharanthus roseus)
Perfect Flower

12. (hermaphrodite)
Calyx (K)
Corolla (C)
Androecium (A)
Gynoecium (G)
Flower diagram

13. Imperfect Flowers
Staminate Pistillate

14. Staminate flowers (left) and carpellate flowers (right)
of a dioecious species
(a)
(b) Thrum and pin flowers
Stamens
StamensStyles
Styles

16. Dichogamy: floral parts mature at different times

17. Methods to ensure cross pollination
Dichogamy :
• Anthers and stigmas mature at different
times in a bisexual flower so as to prevent
self pollination.
- Protandry Anthers mature earlier than
stigma of the same flower. Their pollen
grains become available to stigmas of the
older flowers, e.g., Sunflower, Salvia,
- Protogyny
Stigmas mature earlier so that they get
pollinated before the anthers of the same
flower develop pollen grains, e.g., Mirabilis
jalapa (Four O’Clock), Gloriosa, Plantago.

18. • Since flowers can't move, they need to be able to attract
pollinators or be built so that wind is able to pollinate them.
• Pollinators
– Wind
– Bees
– Butterflies & moths
– insects
– Birds
– Bats
• Flowers attract pollinators with sweet nectar, bright colors, and
shapes and structures.
• Some flowers open at special times to attract pollinators such
as night blooming plants that are pollinated by bats.

19. Image 1. Bee rubbing its hairy body against the filaments.Image 2. Bee carrying thousands of pollen grains on its hairs.

20. Anther
Stigma

21. Reproduction and Development

22. Reproduction and Development

23. Wind pollination in grasses

24. Adaptations for wind pollination

25. Wind Pollinated Insect Pollinated
small petals, often brown or dull
green
large, brightly coloured petals
no scent often sweetly scented
no nectar usually contain nectar
pollen produced in great quantities moderate quantity of pollen
pollen very light and smooth pollen often sticky or spiky
anthers loosely attached and
dangle out
anthers firm and inside flower
stigma hangs outside the flower stigma inside the flower
stigma feathery or net like stigma has sticky coating

26. Bird-pollinated

27. Animals-pollinated

28. Water-pollinated