Pollination

• This is the first step in the process of seed formation.
• The male gamete, present in the pollen grains of the anthers, need to reach the female gamete in the ovary (present in the pistil).
• Only then fertilization takes place.
• The transfer of the pollen grains to the stigma of the pistil is known as pollination.

Pollination is of two types:

Self-pollination

Cross-pollination

Self-pollination:

• In self-pollination, pollen grains are transferred to the stigma of the same flower.

Self pollination

Cross-pollination:

• In cross-pollination, the pollen grains are transferred from the anther of one flower to the stigma of another flower of the same kind.
• Pollination takes place with the help of external agents such as wind, water, and insects. They are called the agents of pollination.

Agents of Pollination:

• The most common agents of pollination are:

      Wind

      Water

      Insects

Wind:

• Wind blows away pollen grains from the anthers of one flower to the stigma of another flower.

Wheat

• Such flowers are small, not brightly coloured, and do not produce nectar (a sweet liquid produced by flowers).
• Pollen grains are very light so they are easily blown away with the wind.
• Male and female gametes are exposed to the wind. Some examples are wheat, rice, and maize.

Water:

• Pollination in aquatic plants such as sea grass and Vallisneria is usually carried out by water.

Vallisneria

• Water-pollinated flowers release their pollen grains into the water, and are slowly carried to other flowers by water currents.

Insects:

• Many insects visit flowers for nectar.
• During the process, some pollen sticks to the body parts of these insects.
• When these insects visit another flower, the pollen grains fall on the stigma.

Insect pollinated flower

• Insect-pollinated flowers usually have sweet smell, bright-coloured petals, and are rich in nectar. Examples are sweet pea, orchids, etc.
• Flowers visited by nocturnal (active during night) insects have less showy petals but are often strongly scented. For example, Jasmine (Raat ki Rani).