1. Pollination

2. Ways of pollination Geitonogamy Autogamy Allogamy Self Pollination
Cross Pollination
Pollination between flowers
of the same plant
Pollination between flowers
of different plants
Geito – neighbour
Allo – other
Auto – self When can self pollination occur?
Gamy - marriage
Geitonogamy
Same plant but a
different flower
Autogamy
Same flower
Allogamy

4. Self pollination Cross pollination Autogamy 1.Allogamy
No agent required 2. Agent is required
Male & female parts 3. Male & female parts
mature at the same time mature at different times
4. Can occur even if the 4. Can occur only when
flower is closed flower is open
5. Offspring can become 5. Offspring healthier
Weak
6. New variety not possible 6. New variety possible
7. Preserves parental 7. Does not preserve
Characters parental characters
Build advantages and disadvantages of self and cross pollination from this.

5. Self pollination Advantages Disadvantages
Pollination is sure 1. Offspring gets weaker
Parental characters 2. New variety not
are preserved possible
3. Fewer pollen grains 3. Weaker strains cannot
are needed eliminated
4. Flowers are not large /
showy/scented /
have nectar

6. Cross pollination Advantages Disadvantages
Healthier offspring 1. Pollination is not
always sure
2. New varieties can be 2. Lot of pollen is produced produced & wasted
3. Seeds are abundant 3. Flowers may have
and good quality to be large, showy, scented, have nectar
Nature favours cross pollination

7. Conditions which favour Cross pollination
Unisexuality – Dioecious plants
Dichogamy – different maturation of androecium and gynoecium - Sunflower
i) anthers mature earlier – protandry e.g. Maize
ii) Stigma matures earlier – protogyny e.g. bajra

8. Self sterility – Even if the stigma receives pollen form the anthers of the same flower, pollen does not undergo further growth. E.g. Ray florets of sun Flower

9. Mechanical or structural barriers – Herkogamy
There may be a hood covering the stigma which can be broken only by agents like the insects e.g. Pansy, Calotropis

10. Anther
Stigma
Anther
Stigma
Heterostyly – Anthers and stigma grow at different heights which does not permit self pollination – Primrose

11. To watch video of insect pollination

12. Interesting Fact
One anther on a maize flower produces 3000 pollen grains. This means that all the anthers on one plant produce a total of around 18 million pollen grains!
To watch video of Wind pollination in Pine trees

13. Water Pollination

14. Insect Pollinated Entomophilous Wind pollinated Anemophilous
Water Pollinated
Hydrophilous
Flower
Large
Coloured,
Scented
Has nectar
Small
Not coloured
Not scented
No nectar
Pollen
Not in large numbers
Sticky or spiny
Large numbers
Dry and light
Loosely attached
Float below the surface of water
Vallisneria pollen float till they meet female flowers
Stigma
Sticky
Does not hang out of the flower
Feathery
Hang out of the flowers
Dioecious

15. Ornithophilous – Bird Pollinated e.g. Begonia, Canna
Elephophilous – Elephant pollinated e.g. Rafflesia