BiologyICSE Class 9 · The Flower

Parts of a Flower and Their Functions (ICSE Class 9 Biology)

Updated 17 October 2026 · Fact-checked

A typical flower has four whorls on the thalamus: calyx (sepals), corolla (petals), androecium (stamens, male) and gynoecium or pistil (carpels, female). Calyx and corolla are accessory whorls; androecium and gynoecium are the essential reproductive whorls. A flower with all four is complete; one lacking any whorl is incomplete.

Understand Parts of a Flower and Their Functions

1. Plan of a flower. The flower is borne on a stalk (*pedicel*) whose tip, the *thalamus* (receptacle), carries four whorls from outside to inside.

2. Accessory whorls.

*Calyx*: sepals, usually green; protect the bud and help photosynthesis.
*Corolla*: petals, usually coloured and scented; attract insects for pollination.

3. Androecium (male). Made of *stamens*, each with a *filament* and an *anther* with pollen sacs that produce pollen grains.

4. Gynoecium or pistil (female). Made of one or more *carpels*, each with a *stigma* (receives pollen), a *style* (stalk that carries the pollen tube) and an *ovary* with one or more *ovules*. After fertilisation the ovule becomes a seed and the ovary becomes a fruit.

5. Kinds of flowers.

*Bisexual* (both androecium and gynoecium, such as hibiscus) and *unisexual* (only one, such as cucumber).
*Complete* (all four whorls) and *incomplete* (any whorl missing).

6. Inflorescence and placentation (meaning only). An *inflorescence* is the arrangement of flowers on the flower stalk (for example sunflower head); *placentation* is the arrangement of ovules inside the ovary.

Parts of a Flower and Their Functions: key facts

Whorls: $C a l y x ∣ C or o l l a ∣ A n d r oec i u m ∣ G y n oec i u m$
Stamen: Filament
Anther
Pollen sacs
Pollen grains
Carpel: $S t i g ma ∣ S t y l e ∣ O v a r y ∣ O v u l es$
Types: Bisexual both essential whorls
Unisexual one
Complete four whorls

Bisexual	both essential whorls
Unisexual	one
Complete	four whorls

Parts of a Flower and Their Functions in real life

The idea, met in an everyday situation. Answer the question in your own words, then compare with the model answer. The one-line hook is what to remember.

A pair of hibiscus flowers

Suppose a student plucks a hibiscus and a cucumber flower and finds that the first has both a long tube with powder and a swollen base, while the second has only powder-bearing parts.

Classify them.

Try it first, then show the solutionSolution

Hibiscus has stamens and pistil: bisexual.
The cucumber flower is unisexual.

Answer: Hibiscus: bisexual; cucumber flower: unisexual (male).

Memory hook: Both or one.

Tricks to remember Parts of a Flower and Their Functions

Short memory aids. Say each one aloud once, then use it on a question the same day.

CCAG
Calyx, Corolla, Androecium, Gynoecium from outside in.
Use it when: Whorls.
SSO
Stigma, Style, Ovary from top to bottom.
Use it when: Carpel.

Parts of a Flower and Their Functions: solved examples

Ordered from board level to HOTS. Try each one before you open the solution.

Example 1: Name · 3 marks · Short answerBoard level

Name the part of the flower that (a) receives pollen, (b) produces pollen, (c) develops into a fruit. [3]

Try it first, then show the solutionSolution

(a) Stigma.
(b) Anther.
(c) Ovary.

Answer: (a) Stigma (b) Anther (c) Ovary.

Example 2: Essential whorls · 2 marks · Short answerBoard level

A flower has all its petals and sepals removed but still sets seed. Which whorls must remain and why are they called essential? [2]

Try it first, then show the solutionSolution

They carry out reproduction.
Without them there are no gametes or seeds.

Answer: The androecium and gynoecium must remain; they are the reproductive parts, producing pollen and ovules.

Example 3: Complete vs bisexual · 3 marks · Short answerHarder board level

Give an example of a flower that is bisexual but incomplete and explain. [3]

Try it first, then show the solutionSolution

Bisexual means both stamens and carpels are present.
Incomplete means a whorl such as petals or sepals is missing.
Example: a flower with both essential whorls but no petals, as in some grasses.

Answer: A flower with stamens and carpels but lacking petals.

Example 4: Seed and fruit · 3 marks · Short answerHarder board level

Trace which parts of a pistil become fruit, seed and what happens to stigma and style. [3]

Try it first, then show the solutionSolution

Ovary becomes the fruit.
Ovules become seeds.
Stigma and style usually wither.

Answer: Ovary: fruit; ovules: seeds; stigma and style wither.

Example 5: Case: the missing parts · 5 marks · Case-basedHOTS / competency

Case. A student studies a flower with sepals, petals and stamens but no pistil. (i) Is it complete? [1] (ii) Is it bisexual? [1] (iii) Can it produce seeds? [1] (iv) Which type of plant might bear it? [2]

Try it first, then show the solutionSolution

(i) No.
(ii) No, it is unisexual (male).
(iii) No, it has no ovule.
(iv) A plant with separate male and female flowers such as cucumber.

Answer: (i) No (ii) No (iii) No (iv) Plants with unisexual flowers.

Where students lose marks in Parts of a Flower and Their Functions

The slips examiners see most often, and what to write instead.

Mistake: Confusing style with stigma
Positions are swapped.
Do this: Stigma at the tip; style below it.
Usually costs: 1 mark.
Mistake: Calling sepals male parts
Whorls mixed.
Do this: Sepals protect; stamens are male.
Usually costs: 1 mark.
Mistake: Using complete for bisexual
Different terms.
Do this: Complete: four whorls; bisexual: both essential parts.
Usually costs: 1 mark.

Exam tips

Draw a labelled L.S. of a flower with every part and function.
Use a table for male and female whorls.
Distinguish bisexual from complete.
Mention that the ovary becomes the fruit.

Practice questions on Parts of a Flower and Their Functions

Write each answer on paper first. Open the hint only if you are stuck, and the answer only when you have finished.

Q1 · 1 mark · MCQBoard level
The stalk of a flower is called the:
(a) thalamus
(b) pedicel
(c) style
(d) filament
Hint
Stalk.
Answer
(b) pedicel.
Q2 · 2 marks · Very short answerBoard level
What is the function of the corolla? [2]
Hint
Attract.
Answer
To attract insects and so help pollination.
Q3 · 2 marks · Very short answerBoard level
Name the female reproductive part of a flower and its parts. [2]
Hint
Pistil.
Answer
Gynoecium or pistil: stigma, style and ovary.
Q4 · 1 mark · Assertion-reasonHarder board level
Assertion (A): Sepals are usually green.
Reason (R): They contain chlorophyll and protect the bud.
(a) Both A and R are true and R is the correct explanation of A.
(b) Both A and R are true but R is not the correct explanation of A.
(c) A is true but R is false.
(d) A is false but R is true.
Hint
Chlorophyll.
Answer
(a).
Q5 · 3 marks · Short answerHarder board level
Compare a stamen and a carpel in structure and role. [3]
Hint
Male/female.
Answer
The stamen has filament and anther and makes pollen; the carpel has stigma, style and ovary and contains ovules.
Q6 · 3 marks · Short answerHarder board level
Distinguish between unisexual and bisexual flowers with one example each. [3]
Hint
Both parts.
Answer
A bisexual flower has stamens and pistil, as in hibiscus; a unisexual flower has only one, as in papaya or cucumber.
Q7 · 2 marks · Very short answerHarder board level
What are an inflorescence and placentation? [2]
Hint
Meaning.
Answer
Inflorescence is the arrangement of flowers on the axis; placentation is the arrangement of ovules inside the ovary.
Q8 · 3 marks · Short answerHarder board level
Why is the stigma sticky or feathery? Link it to the pollination agent. [3]
Hint
Catch.
Answer
A sticky stigma holds pollen brought by insects; a feathery one catches pollen carried by the wind.
Q9 · 4 marks · Case-basedHOTS / competency
Case. A florist cuts off all anthers of a rose to keep it from staining a table. (i) Which whorl is removed? [1] (ii) Can the rose still make seeds if pollinated by another rose? [2] (iii) Why? [1]
Hint
Female intact.
Answer
(i) Androecium. (ii) Yes. (iii) The pistil is intact, so pollen from another flower can fertilise its ovules.
Q10 · 4 marks · Case-basedHOTS / competency
Case. A student draws a flower with three whorls: sepals, stamens and a pistil. (i) Name the missing whorl. [1] (ii) Is it complete? [1] (iii) Is the flower still able to produce a fruit? [2]
Hint
Corolla.
Answer
(i) Corolla. (ii) No. (iii) Yes, if pollinated, since the pistil is present.

Test your recall

Answer in your head or on paper first, then open the card. Pulling an answer out of memory makes it stick far better than re-reading.

1.Outermost whorl?Show answer
Calyx.
2.Pollen producer?Show answer
Anther.
3.Female whorl?Show answer
Gynoecium.
4.Part of the carpel receiving pollen?Show answer
Stigma.
5.Receptacle other name?Show answer
Thalamus.

Parts of a Flower and Their Functions: frequently asked questions

Is a pistil one carpel?

It may be one carpel or many fused.

Which flowers are unisexual?

Cucumber and papaya.

Why are petals bright?

To attract pollinators.