Pollination

Pollination:

• Pollination is a wonderful mechanism which provides food, shelter, etc., for pollinating animals.
• Many plants are pollinated by a particular animal species and the flowers are modified accordingly, and thus there exists a co-evolution between plants and animals.
• Let us imagine if pollination fails. Do you think there will be any seed and fruit formation? If not what happens to pollinating organisms and those that depend on these pollinating organisms for the food? Here lies the significance of the process of pollination.
  

  Pollination

• The pollen grains produced in the anther will germinate only when they reach the stigma of the pistil. The reproductive organs, stamens, and pistil of the flower are spatially separated, a mechanism which is essential for pollen grains to reach the stigma is needed. This process of transfer of pollen grains from the anther to a stigma of a flower is called pollination.
• Pollination is a characteristic feature of spermatophyte (Gymnosperms and Angiosperms).
• Pollination in gymnosperms is said to be direct as the pollens are deposited directly on the exposed ovules, whereas in angiosperms it is said to be indirect, as the pollens are deposited on the stigma of the pistil.
• In the majority of angiosperms, the flower opens and exposes its mature anthers and stigma for pollination. Such flowers are called chasmogamous and the phenomenon is chasmogamy. In other plants, pollination occurs without opening and exposing their sex organs. Such flowers are called cleistogamous and the phenomenon is cleistogamy.
• Pollen grains being non-motile, angiosperms have evolved the strategy to use abiotic agents (wind, water) and biotic agents (birds, insects, snails) to their flowers, feeding the visitors and exploiting their mobility for pollination and also seed dispersal.