Self pollination is the transference of the pollen grains from the anther to the stigma of either the same or genetically similar flower.
Cross pollination is defined is defined as the deposition of pollen grains from anther of a flower to the stigma of a different flower of another plant of same or different species. It is also known as allogamy. There are special devices or arrangement which favour cross pollination.
Importance of Pollination
Self Pollination  | Cross Pollination  |
| It is the transfer of pollen grains from anther to the stigma of either the same or genetically similar flower. | Cross pollination involves the transfer of pollen from anther of one flower to the stigma of a genetically different flower. |
| Self pollination can occur even in closed flower. | It occurs when the flowers are open. |
| External agency is not required for self pollination , except in case of geitonogamy. | An external agent is essential for carrying the pollen grains from anthers to the stigma. |
| The plants ultimately become homozygous. | The plants remain heterozygous. |
| Highly useful characters are preserved by self pollination | Cross pollination is unable to preserve all the highly useful characters since they tend to get diluted. |
| Adaptability to changed environment is absent as self pollination does not produce variability. | Plants are better adapted to changed environment and struggle for existence due to introduction of variations. |
| It does not help in producing new races, varieties and species. | Cross pollination is a mechanism of producing new races, varieties and even species. |
| Self pollination produces pure lines. | It give rise to offspring having variations among themselves. |
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