Pollination

i. Self-Pollination
This type occurs when pollen grains are transferred from the anther to the stigma of the same flower or to another flower on the same plant.
Examples: Garden peas, Dandelion.

ii. Cross-Pollination
This is the transfer of pollen grains from the anther of one plant's flower to the stigma of a flower on a different plant of the same species.
Examples: Maize, Sorghum.

• a. Self-pollination. b. Cross pollination.*

Pollination in plants is aided by various external agents that transfer pollen grains from the anther to the stigma. These agents include:

• Wind
• Water
• Insects
• Bats
• Birds

Based on the agent involved, flowers are generally classified into two major categories:

1. Wind-Pollinated Flowers
2. Insect-Pollinated Flowers

Some flowers rely on wind to carry their pollen grains. These flowers are usually structured in a way that makes them more effective for wind dispersal. The pollen grains are small and lightweight, making it easier for the wind to carry them through the air. The stigma of such flowers is often feathery and sticky, which helps trap the airborne pollen.

Examples: Maize, Grasses

Characteristics of wind-pollinated flowers

1. Dull or not brightly coloured, since they do not attract animals or insects.
2. Small and light pollen grains that can be easily carried by air.
3. Simple floral structure with reduced or absent petals.
4. No scent, as scent is not needed to attract pollinators.
5. No nectar, because nectar is used to attract animals, not wind.
6. Large, feathery stigmas that hang outside the flower to trap pollen grains effectively.

Insects and birds can also serve as pollination agents. When they visit flowers to feed on nectar, pollen grains stick to their bodies. As these pollinators move from flower to flower, some of the pollen they carry is transferred to the stigma of other flowers, facilitating fertilization.

Characteristics of insect pollinated flowers

• Brightly coloured to attract insects and birds.
• Sweet fluid (nectar) is produced as a food source for pollinators like insects and birds.
• Large and sticky pollen grains are covered with spiky hairs to ensure they stick to the bodies of pollinators as they move from one flower to another.