Self-Pollination:
In self pollinated plants, transfer of pollen grains from anther to the stigma of the same flower is facilitated mainly by means of wind and insect. When the flowers are swayed by air currents, the dry pollen grains are transferred from the anther to the sticky stigma. In case of bright colored and sweet scented flowers. Pollinated is effected by insects. When an insect enters into the flower in search of nectar, the spiny pollen grains adhere firmly to its back. As the insect comes out of the flowers or moves inside the flower, the pollen grains are transferred to the sticky stigma as it rubs against the insect’s surface.
Cross Pollination:
Cross pollination is the rule in unisexual flowers. In bisexual flowers cross pollination occurs through some adaptations in flowers.
Self-Pollination vs Cross Pollination:
| Self-Pollination | Cross Pollination |
| 1. It is a certain process | 1. It is an uncertain process |
| 2. Pollen grains are less wasted | 2. Pollen grains are more wasted |
| 3. Offspring are less healthier | 3. Offspring are much healthier |
| 4. Seeds are less visible | 4. Seeds are more visible |
| 5. It takes place between flowers of same genotype or within a single flower | 5. It takes place between flowers of different genotypes. |
| 6. Basic characters are not altered | 6. Basic characters are altered |
| 7. Germinating capacity is not good | 7. Germinating capacity is much better |
| 8. New characters are not formed | 8. New characters are formed |
| 9. Degeneration of species takes place | 9. Gradual prominence of species takes place |
| 10. New species is not formed | 10. New species is formed |
| 11. It has no role in evolution | 11. It plays important role in evolution |
| 12. Quality deteriorates through generation | 12. Quality improves through generation |