4.4 Flowers and pollination

Summary: When you look at a flower, you might only notice its colour or its smell. But what is inside a flower? Why are flowers important? Tags: science oxford-science student-book-7 biology Created: 2026-05-19 Last Updated: 2026-05-19

After this topic, you will be able to:

• describe the function of the main structures in a flower
• describe the process of pollination
• compare the structure of wind-pollinated and insect-pollinated plants.

Think back

1. What are the four main parts of a plant?
2. What do all plants need to survive?
3. Which organ system is in a flower?

Key idea Pollen fertilizes the ovule in pollination.

Key words petal, anther, stigma, pollen, stamen, style, carpel, filament, ovary, ovule, sepal, gamete, pollination

When you look at a flower, you might only notice its colour or its smell. But what is inside a flower? Why are flowers important?

What is inside a flower?

Figure 1Parts of a flower. Full text alternative to the content

Figure 1 shows that inside a flower there are male and female parts:

• The stamen is the male reproductive part – it contains an anther and a filament.
• The carpel is the female reproductive part – it contains a stigma, style, and ovary.

The anther produces pollen grains and the ovary contains ovules. Pollen and ovules are gametes. Gametes are reproductive Cells that join together to create a new organism.

A Name the parts of a flower that produce gametes.

How are new plants made?

A new plant begins with fertilization. Pollen grains, like those in Figure 2, need to fertilize the ovule. For this to happen, pollen from the anther needs to transfer to the stigma. This is called pollination.

Figure 2Pollen grains under a microscope.

Pollination can occur between two different plants. This is called cross-pollination. It can also occur between the male and female parts of the same plant. This is called self-pollination.

B Identify the type of pollination that occurs between two flowers in a garden.

How does pollination happen?

There are two ways that pollen can be transferred to the stigma:

• By the wind – the pollen from the flower of one plant is blown by the wind and might land on the stigma of another plant’s flower.
• By insects – when insects visit the flower, pollen gets stuck to them. When they move to the flowers of another plant, the pollen from the first flower rubs off onto the stigma of the next flower.

Insect-pollinated plants

Most insect-pollinated plants, like the one in Figure 3:

• are a bright colour and smell sweet to attract insects
• contain nectar – a sweet liquid
• produce small quantities of sticky or spikey pollen which sticks to insects
• have their anthers and stigma held inside the flower, so insects can brush against them easily.

Insect pollination is very important in food production. Plants that make fruit, vegetables, and nuts are pollinated by insects.

Figure 3A bee collecting nectar on an insect-pollinated plant. Bees use nectar to make honey.

C Give two ways flowers attract bees.

Wind-pollinated plants

Most wind-pollinated plants, like the one in Figure 4:

• have small petals that are brown or green
• do not produce nectar
• produce large amounts of very Light pollen that is easily carried by the wind
• have anthers and stigmas which hang out of the flower. This makes it easier for the plant to release pollen and to catch pollen from other plants.

Figure 4The flowers of an oak tree. Oak trees are wind-pollinated.

D Explain why the pollen from wind-pollinated plants is very light.

Literacy skills Produce a series of cartoons showing how a plant is pollinated by an insect. Each frame should contain a caption explaining what is happening.

Summary questions

1. Match each part of a flower to its function. anther holds up the anther filament brightly coloured to attract insects stigma produces pollen style contains ovules ovary this is sticky to ‘catch’ pollen grains petal holds up the stigma
2. Pollination can occur in a number of ways. Describe what pollination is.Describe the differences between cross-pollination and self-pollination.
3. Explain two differences between the structure of insect-pollinated and wind-pollinated plants.