The transfer of pollen from a stamen to a pistil; fertilization in flowering plants. It takes place through self-pollination or cross-pollination. Please note that this answer refers specifically to the pollination of angiosperms and gymnosperms.

Self-pollination:

Please see the related link below.

Cross-pollination:

The process in which the pollen from the anther of the male flower of a plant comes into contact with the ovary of a female flower from another plant, resulting in pollination.

Some methods/agents of cross-pollination are:

1. Humans (cultivation)
2. Insects (known as entomophily)
3. Wind (known as anemophily)
4. Animals (birds, bats)

Insects were separated from animals, because of the difference in pollination method.

Cross-pollination only occurs between species of closely related plants; for example, between different varieties of apple. Cross-pollination does not occur between unrelated plant genera, such as between an apple and an orange.

For further elaboration on the methods of cross-pollination, see the related links section. Pollination is the transfer of the pollen grains from the anther to the stigma of a plant.

Agents of Pollination

1. Wind (anemophily): Wind is one of the most important agents of pollination. Pollination brought about through agency of wind in plants is called anemophily. Wind pollinated plants are coconut palm, date palm, cannabis, maize, grasses etc. exhibit the following characters which favour the wind pollination.

a) Wind pollinated flowers are inconspicuous and not showy.

b) They are devoid of scent, nectar etc.

c) The pollen grains are dry and unwettable.

d) The anemophilous plants grow in large groups to ensure pollination.

e) To catch the pollen grains, the stigma become sticky, hairy, and feathery or branched.

2. Water (Hydrophily): Pollination brought about through the agency of water in plants especially submerged plants is termed hydrophily. Examples are Hydrilla, Ceratophyllum, Zostera and Vallisneria are some of the water pollinated plants.

3. Insects(Entomophily): Inset pollinated flowers possess following characteristic features

a) The insect pollinated flowers are fragrant and omit sent and odour. Example Cestrum, Jasmine etc. Rafflesia gives out obnoxious and repelling odour.

b) The insect pollinated flowers are beautifully coloured. In flowers, mostly petals are brightly coloured.

c) The nectariferous glands produce nectar for feeding the visiting insects.

d) To catch the pollen grains, the stigmas become sticky.

4. Birds (ornithophily): Ornithophilous flowers differ in number of respects from entomophilous flowers. These kind of flowers are generally scentless. The flowers are usually large in size. They are also beautifully coloured with colour contrasts and are common colours liked by birds.

5. Bats (Chiropterophily): The flowers of Kigella pinnata, Durio, Antocephalus are pollinated by bats. The bats hold on to the freely exposed, large and relatively tough flowers, which open in the evening or night. Bats are nocturnal animals and transport pollen over long distances. They usually give off a strong scent like that of rotting fruits. Bats also feed on the copious nectar and pollen which is produced in plenty as compared bird pollinated flowers.

Agents of Pollination

1. Wind (anemophily): Wind is one of the most important agents of pollination. Pollination brought about through agency of wind in plants is called anemophily. Wind pollinated plants are coconut palm, date palm, cannabis, maize, grasses etc. exhibit the following characters which favour the wind pollination.

a) Wind pollinated flowers are inconspicuous and not showy.

b) They are devoid of scent, nectar etc.

c) The pollen grains are dry and unwettable.

d) The anemophilous plants grow in large groups to ensure pollination.

e) To catch the pollen grains, the stigma become sticky, hairy, and feathery or branched.

2. Water (Hydrophily): Pollination brought about through the agency of water in plants especially submerged plants is termed hydrophily. Examples are Hydrilla, Ceratophyllum, Zostera and Vallisneria are some of the water pollinated plants.

3. Insects(Entomophily): Inset pollinated flowers possess following characteristic features

a) The insect pollinated flowers are fragrant and omit sent and odour. Example Cestrum, Jasmine etc. Rafflesia gives out obnoxious and repelling odour.

b) The insect pollinated flowers are beautifully coloured. In flowers, mostly petals are brightly coloured.

c) The nectariferous glands produce nectar for feeding the visiting insects.

d) To catch the pollen grains, the stigmas become sticky.

4. Birds (ornithophily): Ornithophilous flowers differ in number of respects from entomophilous flowers. These kind of flowers are generally scentless. The flowers are usually large in size. They are also beautifully coloured with colour contrasts and are common colours liked by birds.

5. Bats (Chiropterophily): The flowers of Kigella pinnata, Durio, Antocephalus are pollinated by bats. The bats hold on to the freely exposed, large and relatively tough flowers, which open in the evening or night. Bats are nocturnal animals and transport pollen over long distances. They usually give off a strong scent like that of rotting fruits. Bats also feed on the copious nectar and pollen which is produced in plenty as compared bird pollinated flowers.