Parts of a Complete Flower

1A complete flower

Flowers are the reproductive organs of flowering plants. A complete flower has all four kinds of parts: sepals, petals, stamens (male) and a pistil (female). Hibiscus, bean and passion-fruit flowers are complete flowers.

2The outer parts

• Flower stalk (pedicel): holds the flower up and attaches it to the branch.
• Receptacle: the top of the stalk, where all the other parts are attached.
• Sepals: small, green, leaf-like parts that protect the flower while it is a bud. All the sepals together are called the calyx.
• Petals: usually big and brightly coloured, often scented, to attract insects and birds. All the petals together are called the corolla. Grasses and maize have tiny petals or none, because the wind, not animals, carries their pollen.

3The male part: the stamen

The stamen has two parts:

• the anther, which makes pollen. Pollen grains carry the male sex cells.
• the filament, a thin stalk that holds the anther up.

4The female part: the pistil (carpel)

The pistil, also called the carpel, is usually in the centre of the flower. It has three parts:

• the stigma, the sticky top that receives pollen;
• the style, a tube joining the stigma to the ovary;
• the ovary, the swollen base. Inside it are ovules, which contain the female sex cells (egg cells).

After fertilisation, each ovule becomes a seed and the ovary becomes the fruit.

5Summary table

6Activity: take a flower apart

With your teacher, collect a large flower such as a hibiscus. Carefully remove the sepals, then the petals. Find the stamens and the pistil with a hand lens. Your teacher can cut the ovary in half with a blade so you can see the tiny ovules. Draw the flower and label it, using a ruler for straight label lines that do not cross. Wash your hands afterwards.

Try it yourself

1. Which part of a flower makes pollen?
2. Name the three parts of the pistil.
3. What is the job of the sepals?
4. Why do maize flowers not need big, bright petals?
5. Which part of the flower becomes a seed?

Answers

1. The anther.
2. Stigma, style and ovary.
3. They protect the flower while it is still a bud.
4. Maize is pollinated by the wind, so it does not need to attract insects or birds.
5. The ovule.