Friday, 27 March 2015

POLLINATION


Pollination is the mechanism to transfer  pollen grains from  the anther to the stigma of a pistil is termed pollination.


                                  

                               






KINDS OF POLLINATION


Depending on the source of pollen, pollination can be divided into three.

Autogamy            

Transfer of pollen grains from the anther to the stigma of same flower is called autogamy or self-pollination.



Geitonogamy  

    Transfer of pollen grains from the anther to the stigma of another flower of same plant is called geitonogamy.



Xenogamy     

     Transfer of pollen grains from the anther to the stigma of a different plant is called xenogamy.




AGENTS OF POLLINATION

Pollinating agents are either abiotic (wind and water) or biotic (animals).

Pollination by wind  

Wind pollination is more common amongst abiotic pollination. Wind pollination requires that the pollen grains are light and non-sticky so that they can be transport easily. And the plants have well exposed stamens and large often feathery stigma to easily trap pollen grains.

Pollination by water  

Aquatic plants may have aerial, submerged or floating flowers.   It is quite rare in flowering plants.  And the plants have well exposed stamens and large often feathery stigma to easily trap pollen grains.

Pollination by Animals

              Insect pollination

Flowers are mostly pollinated by insects. When an insect visiting a flower to collect food (nectar) pollen from the stamens sticks to the insect and then it travels to another flower these pollen grains are sticks to stigma of the flower.       

                     




                           









        Bird pollination

Many bird pollinated flowers are bright coloured (red or orange) to attract birds, flowers are large in size and most are tubular so that bird can dip their beaks in. while pollen grains from stamen sticks on birds head and pollination occurs.

                                           



                           




     Mammal pollination

Some types of bats and Australian possum are the important mammal pollinators. They pollinate flowers by feed on nectar and pollen.





 











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