Pollination

Pollination is the process by which pollen is transferred from the male anthers of a flower to the female stigma of a flower. This process is essential for the reproduction of plants and is typically carried out by insects, birds, small mammals or the wind.

Pollen comes in many sizes and forms, depending on the plant species; for example:

  • Some pollen grains are small and lightweight, allowing them to be transported easily by the wind.
  • Some pollen grains are larger and sticky, with spikes or other structures that help them attach to insects.

In wind-pollinated plants, the pollen produced by the anthers is released into the air and carried by the wind to other plants, where it may be caught by the stigma. In insect-pollinated plants, pollen is transferred from flower to flower by insects. They visit the flowers for nectar or to feed on pollen.

The table below compares the properties of insect-pollinated plants and wind-pollinated plants.

This image has an empty alt attribute; its file name is image-17.pngThis image has an empty alt attribute; its file name is image-16.png
FeatureWind pollinatedInsect pollinated
PetalsSmall dull petals, as there is no need to attract insectsBrightly coloured petals to help attract pollinating insects
NectarDo not produce nectarThey produce nectar, which is a sugary fluid to attract bees
Amount of Pollen grainsProduces large amounts of pollen – However, most pollen grains will not get to another flowerThey produce smaller amounts of pollen, as insects are efficient at transferring pollen
AnthersHangs outside of the flower, attached to the long filaments, so the pollen can be taken away by the windHeld firmly inside the flower, so any landing insects will brush against it
StigmaFeathery or sticky and hanging outside of the petals to make it easier to trap pollen that is carried by the windSmall and held inside the flower

Types of Pollination

There are two main types of pollination:

  • Self-pollination – Occurs when the pollen from the anther of a flower is transferred to the stigma of the same flower.
  • Cross-pollination – Occurs when pollen is transferred from the anther of one flower to the stigma of a different flower, usually of the same species.

Graphic representation of two types of pollination in flowers. On the left, a yellow flower labelled "Self Pollination" shows pollen transfer within the same flower, indicated by arrows pointing from its anthers to its stigma. On the right, a two-coloured illustration displays "Cross Pollination" between a coral flower and a blue flower, with arrows illustrating the pollen moving from the anther of the coral flower to the stigma of the blue flower. Both flowers have distinct anthers, stigmas, and petals.