Kinds of Pollination - Cross Pollination

Cross pollination:

• It refers to the transfer of pollen on the stigma of another flower.
• The cross-pollination is of two types: Geitonogamy and Xenogamy

1. Geitonogamy: When the pollen deposits on another flower of the same individual plant, it is said to be geitonogamy. It usually occurs in plants which show monoecious conditions. It is functionally cross-pollination but is generally similar to autogamy because the pollen comes from the same plant.

2. Xenogamy: When the pollen (genetically different) deposits on another flower of a different plant of the same species, it is called xenogamy. This is the only type of pollination which during pollination brings genetically different types of pollen grains to the stigma.

Advantages of cross pollination:

1. Cross pollination introduces genetic recombination and hence the variation in offspring.
2. Cross pollination increases the ability of the offspring to adapt to various changes in the environment.
3. The defective character of race is eliminated and replaced by a better character. 

Disadvantages of cross pollination:

1. Plants have to produce a large number of pollen grains.
2. The good characters are likely to be spoiled.
3. As an external agency is involved chance factor is always there.