Parts of a Plant-the Flower

In this article we explain the function of different parts of the flower.

The buds in this picture are beginning to bloom and become flowers. The green leaves on the outside of a bud are called ‘sepals’. The ‘sepals’ protect the flowers when the flower is ‘in bud’. The sepals  also support the ‘petals’ when the flower is ‘in bloom’.

flower buds petals and sepals

You can clearly see the green sepals on these blueberry flowers which have flowered.

White Blueberry flowers showing sepals

This image shows a primrose willow herb after it has flowered. You can clearly see the sepals and petals. Notice how the sepals are underneath the petals.

primrose willow herb showing sepals and petals

With some flowers it can be more difficult to identify sepals and petals.This white tulip has three sepals and three petals.

  • Can you identify the sepals and petals?
tulip petals and sepals are difficult to identify

© Derek Ramsey, Chanticleer Garden,Wayne Pennsylvania

The petals of this Angel’s Trumpet are all joined together (‘fused’) to form one petal.

  • Where are the sepals?

orange angel's trumpet flower showing petals all fused together

Why are petals brightly colored?

Why have flowers developed brightly colored, sweet smelling and unusually shaped leaves?

passiflora showing unusually shaped leaves and stamen

Flowers want to encourage certain ‘visitors’ to land on their petals. So the petals are often (but not always) a sort of ‘airfield’ designed to attract certain ‘visitors’ to land on.

airport landing lights showing aircraft where to land

What visitors do plants want to attract?

Flowers want to attract all sorts of visitors including bees. This bee has landed on the petals of an aster flower looking for nectar.

Amazing detail of a Bee sitting on an aster flower to extract nectar

Other visitors looking for food include ‘painted lady’ butterflies…

Australian painted lady butterfly feeding showing incredibly long proboscis


purple throated humming birds….

purple throated carib humming bird feeding while hovering next to flower

and lesser long nosed bats.

bat pollinator

© Merlin D.Tuttle Bat Conservation International

You can clearly see the food that visitors to this camelia flower are looking for among the ‘stamens’.This camelia flower is offering a meal of ‘nectar’ which is a type of sugar.

stamen of red camelia flower showing nectar

Not all nectar is as easy to find as the nectar on this camelia flower. Sometimes nectar can be difficult to reach.

Some insects have developed special ‘tongues’ to help them feed on nectar which can be difficult to reach. An insect ‘tongue’ is called a ‘proboscis’ and an insect ‘proboscis’ can be far longer than any human tongue.

A proboscis works much like a straw. The insect uses it proboscis to suck up nectar into its ‘mouth’.

Drinking Straws analogous to an insect sucking up nectar through its proboscis

Look how long the proboscis is of this fly!

fly with long proboscis feeding on nectar of a yellow flower

The giant hawk moth has an even longer proboscis! Its proboscis reaches the nectar of flowers that other insects cannot reach! Amazing!

giant hawk moth showing amazingly long proboscis

Why do flowers provide insects with food?

This is a picture of some ‘stamens’ in the middle of an amaryllis flower. A stamen is made up of an ‘anther’ and a ‘filament’.An ‘anther’ makes a sticky powder called ‘pollen’. The ‘filament’ is the stalk that supports the ‘anther’.Tulip Stamen showing sticky pollen

amaryllis stamen showing anthers and filaments

  • If you go back and look at the other flowers in this school science article, can you spot the ‘stamens’?

When insects land near ‘stamens’ looking for a meal of nectar their bodies brush up against the ‘anthers’. This results in grains of pollen sticking to the bodies of insects.

Look at pollen sticking to this marmalade hoverfly as it sucks nectar from a rock rose. A  small meal of nectar from a rock rose results in pollen sticking to its body.

  • What now happens to the pollen which has stuck to the hoverfly’s body?

hoverfly lands on stamen and pollen sticks to its body as it feeds

Parts of a flower- the ‘stigma’.

After the hoverfly has feasted on the nectar of one rock rose it will visit other rock roses in search of more nectar.

As the hoverfly lands on the petals of a second rock rose it will search for nectar among the stamen of the second rock rose.

purple rock roses in a flower bed showing stamens and leaves

Some of the pollen sticking to its body from the visit to the first rock rose will drop off and fall onto the ‘stigma’ of the second rock rose. The ‘stigma’ is a hollow tube which can be found among the stamen of most flowers. If only one tiny grain of pollen falls onto the stigma that will be enough for the rock rose to produce a seed.

You can see the stigma of a lily flower below. The stalk supporting the ‘stigma’ is called the ‘style’

  • Can you name the ‘reproductive’ parts of this Christmas lily? (answers at bottom of page)

christmas lily showing anthers, stigma, stamens, filaments

Reproductive parts of a flower

Once a grain of pollen has been caught by the stigma the process of making seeds begins. How does a plant make seeds once the stigma has captured a grain of pollen? That’s another story!

diagram of flower showing stigma, stamen, filament, anther, ovule and ovary

Science Projects-parts of a flower

School wall display showing a clearly labelled parts of a daffodil

Collace Primary School, Perth, Scotland

*Answers to reproductive parts of Christmas lily: (in order) stigma, style, anther, filament,petal

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