BiologyICSE Class 9 · Chapter 4

Pollination ICSE Class 9: Self and Cross-Pollination, Agents and Adaptations of Flowers

Updated 15 October 2026 · Fact-checked

Pollination is the transfer of pollen grains from the anther to the stigma. In self-pollination pollen reaches the stigma of the same flower or plant; in cross-pollination it reaches a flower on another plant of the same kind, carried by insects, wind, water or other animals. Flowers show features suited to their agent.

What Pollination is about

Before a seed can form, pollen must reach a stigma. This transfer is pollination. It is the first step of sexual reproduction in flowering plants and is followed by fertilisation.

The CISCE 2028 syllabus (Class IX, Flowering Plants (ii)) covers: self- and cross-pollination, their explanation, advantages and disadvantages; agents of pollination and the characteristic features of flowers pollinated by insects, wind and water; and a brief idea of how nature favours cross-pollination.

Weightage: CISCE publishes no chapter weightage for ICSE Biology. Pollination is topic 2, Flowering Plants (ii), of the Class IX part of the 2028 syllabus; the Class IX paper (80 marks, 2 hours) is set and marked by the school.Source: CISCE ICSE Biology (Science Paper 3) syllabus, examination year 2028 (Class IX)

Key concepts

Self-pollination

Self-pollination: transfer of pollen from the anther to the stigma of the same flower (autogamy) or of another flower on the same plant (geitonogamy). Examples: pea, wheat, rice, sweet pea.

Conditions that favour it:

Bisexual flowers in which anthers and stigma mature at the same time (homogamy).
Flowers that never open (cleistogamy), e.g. some flowers of balsam, oxalis, groundnut, so only their own pollen can reach the stigma.
Anthers placed close to, or above, the stigma.

Advantages:

Sure: no outside agent is needed, so pollen is not wasted.
Keeps the parental characters pure (pure lines).
Flowers need not be large, coloured or scented, so less energy is spent.

Disadvantages:

No new combinations of characters: less variety, so less ability to adapt.
Over generations, offspring may become weaker (lower vigour and yield).
Defective characters cannot be removed.

Worked example

Why do flowers that are self-pollinated usually not have bright colours or nectar?

Try it first, then show the solutionSolution

They do not depend on insects to carry pollen.
Making colour, scent and nectar would waste energy.

Answer: No pollinator to attract.

Cross-pollination

Cross-pollination: transfer of pollen from the anther of a flower to the stigma of a flower on another plant of the same species. It needs an external agent. Examples: papaya, maize, mustard, sunflower, apple.

Advantages:

Offspring get characters from two parents: new combinations (variation).
Offspring are usually healthier and more vigorous, with better yield and resistance to disease.
Helps plants adapt to changing conditions; new varieties can be bred.

Disadvantages:

Uncertain: depends on an outside agent.
Wasteful: much pollen must be made (especially for wind).
Flowers must invest in colour, scent and nectar (for animal pollinators).
Good characters may be lost or unwanted ones added.

Worked example

Give one advantage of self-pollination that is a disadvantage of cross-pollination.

Try it first, then show the solutionSolution

Self-pollination is certain; cross-pollination is uncertain because it depends on an agent.

Answer: Certainty of pollination.

Insect pollination (entomophily)

Insects such as bees, butterflies and moths visit flowers for nectar and pollen and carry pollen on their bodies. Examples: sunflower, rose, salvia, mustard.

Features of insect-pollinated flowers:

Large, brightly coloured petals (or coloured sepals or bracts); white flowers for night insects.
Scented, with nectar (nectaries).
Pollen grains few, large, sticky or spiny (to stick to the insect).
Stigma sticky, often inside the flower where the insect brushes it.
Anthers and stigma placed so that the insect touches both (e.g. the lever mechanism of salvia, where a visiting bee pushes a lever that brings the anthers down on its back).
Often a landing platform and markings (honey guides) leading to nectar.

Worked example

Why are the pollen grains of insect-pollinated flowers sticky or spiny?

Try it first, then show the solutionSolution

They must cling to the insect's hairy body.
They are carried until the insect brushes them on to a sticky stigma.

Answer: To stick to the pollinating insect.

Wind pollination (anemophily)

Wind carries pollen in grasses and cereals such as maize, wheat, rice, and in trees such as pine and date palm.

Features of wind-pollinated flowers:

Small, dull, not scented, no nectar (no need to attract animals).
Petals small or absent, so they do not block the wind.
Pollen produced in huge amounts; grains small, light, dry and smooth (some have air sacs, as in pine).
Anthers on long filaments that hang out of the flower (versatile anthers that swing in the breeze).
Stigmas large, feathery or branched and hang out to catch pollen (the 'silk' of maize).
Flowers often borne high, above the leaves, or open before leaves appear.

Worked example

Why do wind-pollinated plants produce enormous amounts of pollen?

Try it first, then show the solutionSolution

Wind carries pollen in all directions at random.
Most of it never reaches a stigma.
Large numbers make it likely that some grains land on the right stigma.

Answer: Because wind pollination is wasteful and chancy.

Water pollination (hydrophily)

Water carries pollen in a few aquatic plants such as Vallisneria (eel grass), Hydrilla and sea grasses (Zostera). (Many water plants like lotus and water lily are actually pollinated by insects.)

Features:

Flowers small, inconspicuous; no colour, scent or nectar.
Pollen grains often light, with a mucilage or waxy coat that protects them from wetting, or long and thread-like (in sea grasses).
Stigma long and sticky (or unwettable).

In Vallisneria, male flowers break free and float to the surface; female flowers reach the surface on long, coiled stalks. Floating male flowers drift against the female flowers and pollen is transferred; the stalk then coils and pulls the female flower under water.

Worked example

In Vallisneria, how do the female flowers reach the surface, and what happens after pollination?

Try it first, then show the solutionSolution

They grow on long stalks that bring them up to the water surface.
After pollination, the stalk coils and pulls the flower down for the fruit to develop under water.

Answer: Long stalks; the stalk coils back after pollination.

How nature favours cross-pollination

Many bisexual flowers have devices that prevent self-pollination, so cross-pollination is favoured:

Unisexuality: flowers have only stamens or only carpels (maize, cucumber); plants may be entirely male or female (papaya).
Dichogamy: anthers and stigma of a flower mature at different times.
Protandry: anthers ripen first (sunflower, salvia).
Protogyny: stigma ripens first (custard apple, magnolia).
Self-sterility (self-incompatibility): a flower's own pollen cannot germinate on its stigma (tobacco, potato).
Herkogamy: a physical barrier between anther and stigma (e.g. in Calotropis and orchids the pollen is in sacs that only insects can remove).
Heterostyly: flowers on different plants have styles and stamens of different lengths, so pollen from one type fits the stigma of the other (primrose).
Position: stigma held above or away from the anthers.

Worked example

A sunflower's anthers release pollen before the stigmas of the same floret open. Name this device and explain how it favours cross-pollination.

Try it first, then show the solutionSolution

Anthers maturing first is protandry (a type of dichogamy).
By the time the stigma is ready, the floret's own pollen has gone, so it must receive pollen from another flower.

Answer: Protandry.

Pollination in real life

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

Bees and fruit orchards

Suppose an apple grower notices far fewer apples one year after neighbouring farms sprayed heavy insecticide during flowering, and starts renting beehives.

Explain the drop in yield and why the hives help.

Try it first, then show the solutionSolution

Apple flowers are insect-pollinated and need cross-pollination.
Insecticide killed many bees, so fewer flowers were pollinated and fewer fruits formed.
Hives bring bees back to carry pollen between trees.

Answer: Fewer pollinators meant less pollination; hives restore it.

Memory hook: No bees, no apples.

Hay fever in grass season

Suppose a student's hay fever gets worse every year when the grasses near her school flower, though she is not troubled by roses in the garden.

Explain using features of wind- and insect-pollinated flowers.

Try it first, then show the solutionSolution

Grasses are wind-pollinated: they release huge amounts of light, dry pollen that floats in the air and is breathed in.
Roses are insect-pollinated: their pollen is fewer, heavier and sticky, so it stays on the flower or the insect.

Answer: Wind-blown grass pollen enters her nose; rose pollen does not float.

Memory hook: Dusty pollen flies; sticky pollen stays.

Hand pollination of maize

Suppose a seed company wants to cross two maize varieties and covers the tassels (male flowers) of one plant with paper bags.

Why is this needed for maize, and what is done next?

Try it first, then show the solutionSolution

Maize is wind-pollinated, so pollen could come from any nearby plant.
Bagging prevents unwanted pollen from reaching or leaving the flowers.
Pollen from the chosen variety is then dusted on the silks (stigmas) and the cobs are bagged again.

Answer: To control the source of pollen in a wind-pollinated crop.

Memory hook: Bag the flower, choose the father.

Topics in this chapter

Self and Cross Pollination and Agents of Pollination

Pollination: key facts

Pollination: $pollen: anther \to stigma$; Precedes fertilisation.
Self versus cross: $same flower/plant (self); another plant of the species (cross)$; Cross needs an agent.
Agents: $insects (entomophily), wind (anemophily), water (hydrophily)$; Also birds and bats.
Devices for crossing: $unisexuality, dichogamy, self-sterility, herkogamy, heterostyly$; Nature favours cross-pollination.

Pollination: diagrams to practise

Practise each one on paper: draw it from the checklist, then tick off every label.

Wind-pollinated flower (e.g. grass)

Draw a wind-pollinated flower showing its adaptations.

Draw

A small flower enclosed by tiny scales (no showy petals).
Three stamens on long, thin filaments hanging outside with large swinging anthers.
Two large feathery stigmas sticking out.

Label

feathery stigma
anther on long filament
light dry pollen
small dull flower

Watch out: Show pollen grains as dots blowing away.

Pollination in Vallisneria

Show how Vallisneria is pollinated by water.

Draw

A water surface line.
Male flowers floating freely on the surface.
A female flower at the surface on a long, coiled stalk from the plant at the bottom.
A male flower touching the female flower.

Label

water surface
floating male flower
female flower
long coiled stalk
pollen transfer

Watch out: Draw the stalk as a spring to show coiling.

How the school exam asks Pollination

The question patterns to expect, and the method that works for each.

Question type	How it is asked	Method
Definitions	Define pollination, self- and cross-pollination, protandry, protogyny, cleistogamy.	One line + example.
Advantages and disadvantages	Give two each for self- and cross-pollination.	Certainty and purity versus variety and vigour.
Features of flowers	Compare insect- and wind-pollinated flowers; identify the agent from a description.	Use the comparison: petals, scent, nectar, pollen, stigma, anthers.
Devices	How does a bisexual flower avoid self-pollination? Name the device in a given example.	Match example to device.
Application	Predict the agent or effect, e.g. why fruit set falls when bees decline.	Reason from the features.

Tricks to remember Pollination

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

Insect vs wind: 'Bright and Sticky' vs 'Dull and Dusty'
Insect flowers are bright, scented, sticky; wind flowers are dull, scentless, with dusty light pollen.
Use it when: Comparing adaptations.
Protandry = anthers first
Andro = male: PROTANDRY, male parts PROnto first; protoGYNY, female first.
Use it when: Types of dichogamy.
Self = Sure but Same
Self-pollination is Sure but gives the Same offspring; cross is chancy but creates change.
Use it when: Advantages and disadvantages.
Cleisto = closed
Cleistogamous flowers stay closed: guaranteed self-pollination.
Use it when: Conditions for self-pollination.

Pollination: exam-level solved questions

Ordered from exam level to HOTS. Cover the solution, write your own, then compare step by step.

Example 1: Wind-pollinated feature · 1 mark · MCQExam level

Which feature is typical of a wind-pollinated flower?
(a) large, coloured petals
(b) sticky, spiny pollen
(c) feathery stigma hanging out of the flower
(d) strong scent

Try it first, then show the solutionSolution

A feathery stigma catches airborne pollen.

Answer: (c)

Example 2: Cleistogamy · 1 mark · Assertion-reasonHarder exam level

Assertion (A): Cleistogamous flowers are always self-pollinated.
Reason (R): Cleistogamous flowers never open.
(a) Both (A) and (R) are true, and (R) is the correct explanation for (A).
(b) Both (A) and (R) are true, but (R) is not the correct explanation for (A).
(c) (A) is true and (R) is false.
(d) (A) is false and (R) is true.

Try it first, then show the solutionSolution

Closed flowers cannot receive outside pollen, so only their own pollen reaches the stigma.

Answer: (a)

Example 3: Advantages and disadvantages · 3 marks · Short answerExam level

Give two advantages and one disadvantage of cross-pollination.

Try it first, then show the solutionSolution

Advantage: new combinations of characters (variation).
Advantage: healthier, more vigorous offspring.
Disadvantage: uncertain, needs an agent (or wasteful of pollen).

Answer: As above.

Example 4: Compare the flowers · 4 marks · Short answerExam level

Give four differences between insect-pollinated and wind-pollinated flowers.

Try it first, then show the solutionSolution

Petals: large, bright versus small, dull or absent.
Scent and nectar: present versus absent.
Pollen: few, large, sticky versus many, small, light, dry.
Stigma: small, sticky inside the flower versus large, feathery, hanging out.

Answer: As above.

Example 5: Name the device · 3 marks · Short answerHarder exam level

Name the device favouring cross-pollination in each: (a) papaya, (b) potato flowers whose own pollen does not germinate on their stigma, (c) custard apple whose stigma ripens before its anthers.

Try it first, then show the solutionSolution

(a) Unisexuality (separate male and female plants).
(b) Self-sterility (self-incompatibility).
(c) Protogyny (dichogamy).

Answer: As above.

Example 6: Explain Vallisneria · 3 marks · Short answerHarder exam level

Describe how pollination takes place in Vallisneria and give two features of water-pollinated flowers.

Try it first, then show the solutionSolution

Male flowers break off and float on the water; female flowers reach the surface on long stalks.
Floating male flowers touch the female flowers and pollen reaches the stigma; the stalk then coils and draws the female flower under water.
Features: small, inconspicuous flowers; pollen protected from wetting (mucilage).

Answer: As above.

Example 7: Identify the agent · 3 marks · Short answerHOTS / competency

A plant has small greenish flowers in hanging catkins, no scent, and anthers that release clouds of yellow dust when shaken. A second plant has deep red tubular flowers with lots of dilute nectar and no scent, and is often visited by sunbirds. Name the pollinating agent of each and give one reason each.

Try it first, then show the solutionSolution

First: wind (dull, scentless, abundant dry pollen, hanging anthers).
Second: birds (bright red, tubular, plenty of nectar; birds see red but have a poor sense of smell, so no scent is needed).

Answer: Wind; birds.

Example 8: Why crops are kept self-pollinated · 3 marks · Short answerHOTS / competency

Wheat and rice varieties are largely self-pollinated, yet plant breeders cross them deliberately to make new varieties. Explain both facts.

Try it first, then show the solutionSolution

Self-pollination keeps a good variety pure: farmers can sow saved seed and get the same crop.
But it creates no new combinations.
Breeders cross-pollinate by hand to combine useful characters (e.g. yield and disease resistance), then self-pollinate the new type to keep it pure.

Answer: Self-pollination preserves; crossing creates.

Case-study practice (Section B style)

Read the situation, then answer every part. In a school exam set on the board pattern this is a 5-mark question split into 2 + 1 + 2 marks.

The salvia flower

Suppose a student watches a bee land on the lower lip of a salvia flower. As it pushes into the tube for nectar, two anthers swing down and tap its back. In older flowers, the stigma hangs lower and touches the bee's back instead.

(i) · 2 marks
Name the agent of pollination and two features of salvia that attract it.
Answer
Answer: Insect (bee); coloured petals with a landing lip and nectar.
(ii) · 1 mark
The anthers mature before the stigma in each flower. Name this device.
Answer
Answer: Protandry (dichogamy).
(iii) · 2 marks
Explain how the bee brings about cross-pollination.
Answer
Answer: In young flowers pollen is dusted on its back; when it visits an older flower on another plant, the lowered, mature stigma touches its back and picks up that pollen.

Where the marks are

How a typical answer is split into step marks. Show every step: a right final answer alone rarely earns full marks.

Define self-pollination and give two conditions that favour it. (2 marks) (2 marks)

Step	Marks
Transfer of pollen from anther to stigma of the same flower or another flower of the same plant	1
Bisexual flowers with anthers and stigma maturing together; cleistogamy	1

Give three features of wind-pollinated flowers. (3 marks) (3 marks)

Step	Marks
Small, dull, scentless, no nectar	1
Large amounts of light, dry, smooth pollen	1
Feathery stigmas and anthers on long filaments hanging out	1

Where students lose marks in Pollination

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

Mistake: Pollination confused with fertilisation
Both are steps in sexual reproduction.
Wrong working
Pollination is the fusion of male and female gametes.
Right working
Pollination is transfer of pollen to the stigma; fertilisation is fusion of gametes in the ovule.
Do this: Pollination = transfer; fertilisation = fusion.
Usually costs: 1 mark.
Mistake: Defining cross-pollination as 'between two flowers'
Two flowers on the same plant give only self-pollination genetically.
Wrong working
Cross-pollination is the transfer of pollen from one flower to another.
Right working
... to a flower on another plant of the same species.
Do this: Say 'another plant'.
Usually costs: 1 mark.
Mistake: Protandry and protogyny swapped
Students guess which organ ripens first.
Wrong working
Protandry: stigma matures first.
Right working
Protandry: anthers first; protogyny: stigma first.
Do this: Andro = male (anther).
Usually costs: 1 mark.
Mistake: One-sided comparisons
Only insect flowers are described in a 'difference' question.
Wrong working
Insect-pollinated flowers have bright petals.
Right working
Insect: bright, large petals; wind: small, dull or no petals.
Do this: Write both sides of every point.
Usually costs: 1/2 mark per point.

Practice questions on Pollination

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 · MCQExam level
Pollination by water occurs in:
(a) maize
(b) Vallisneria
(c) sunflower
(d) rose
Hint
Eel grass.
Answer
(b)
Q2 · 1 mark · MCQExam level
Which feature favours self-pollination?
(a) protandry
(b) unisexual flowers
(c) cleistogamy
(d) self-sterility
Hint
Closed flowers.
Answer
(c)
Q3 · 2 marks · Short answerExam level
Give two advantages of self-pollination.
Hint
Sure and pure.
Answer
It is certain (no agent needed, less pollen wasted) and keeps parental characters pure (also no need for showy flowers).
Q4 · 1 mark · Very short answerExam level
Name the agent of pollination: (a) maize, (b) salvia, (c) Hydrilla.
Hint
Wind, insect, water.
Answer
(a) Wind (b) Insects (bees) (c) Water
Q5 · 2 marks · Short answerHarder exam level
Why do wind-pollinated flowers lack nectar and bright petals but have long filaments?
Hint
No animals to attract.
Answer
They do not need to attract animals, so nectar and colour would waste energy. Long filaments hold anthers out in the wind so pollen is easily blown away.
Q6 · 2 marks · Short answerHarder exam level
Explain heterostyly and how it favours cross-pollination.
Hint
Different lengths.
Answer
Plants of one species have flowers of two types with styles and stamens of different lengths (e.g. primrose). An insect picks up pollen at one height and delivers it to a stigma at the same height in the other type of flower, on another plant.
Q7 · 3 marks · Short answerHarder exam level
A gardener grows only one plant of a self-sterile variety of fruit tree in an isolated garden. Predict the fruit yield and explain. What should he do?
Hint
Needs another plant.
Answer
Little or no fruit: its own pollen cannot fertilise its flowers, and there is no other plant of the species to provide pollen. He should plant a second compatible variety nearby.
Q8 · 3 marks · Short answerHarder exam level
State two disadvantages of cross-pollination and explain why plants still favour it.
Hint
Variation.
Answer
Disadvantages: uncertain (needs an agent); wasteful of pollen (or costly to make nectar and colour). Plants still favour it because it produces variation and vigorous offspring, helping the species adapt and survive.
Q9 · 2 marks · Short answerHarder exam level
Distinguish between protandry and protogyny with one example each.
Hint
Which matures first.
Answer
Protandry: anthers mature before the stigma (sunflower, salvia). Protogyny: stigma matures before the anthers (custard apple, magnolia).
Q10 · 3 marks · Short answerHOTS / competency
In a sealed greenhouse with no insects and no fans, cucumber plants flower well but set very little fruit, while tomato plants set fruit normally. Explain the difference and suggest a remedy for the cucumbers.
Hint
Unisexual versus bisexual.
Answer
Cucumber flowers are unisexual and need pollen carried from male to female flowers by insects; with none present, few are pollinated. Tomato flowers are bisexual and self-pollinate (helped by slight vibration). Remedy: introduce bees or hand-pollinate with a brush.
Q11 · 3 marks · Short answerHOTS / competency
A flower is large, white, strongly scented in the evening and has a long, narrow tube with nectar at the bottom. (a) Suggest its pollinator. (b) Give a reason for each feature. (c) Is self- or cross-pollination more likely? Explain.
Hint
Night insect with a long tongue.
Answer
(a) A moth. (b) White shows in dim light; evening scent guides night fliers; long tube suits the moth's long proboscis and keeps nectar for it. (c) Cross-pollination: the moth carries pollen from flower to flower on different plants as it feeds.

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.Pollination by insects is called?Show answer
Entomophily.
2.Name a water-pollinated plant.Show answer
Vallisneria (also Hydrilla).
3.Anthers mature before the stigma: term?Show answer
Protandry.
4.Flowers that never open?Show answer
Cleistogamous flowers.
5.Type of stigma in wind-pollinated flowers?Show answer
Large and feathery.
6.One disadvantage of self-pollination?Show answer
No variation; offspring may become weaker.
7.Device in papaya favouring cross-pollination?Show answer
Unisexuality (separate male and female plants).
8.Pollination by wind is called?Show answer
Anemophily.

Best order to study it

Learn the definitions of pollination, self- and cross-pollination.
Learn advantages and disadvantages as a two-column table.
Learn insect, wind and water flower features; make an insect-versus-wind table.
Learn devices favouring cross-pollination with one example each.
Practise identifying agents from descriptions.

Quick revision checklist

The night before the exam: can you do each of these without looking?

Can you define self- and cross-pollination precisely?
Can you give two advantages and two disadvantages of each?
Can you list four differences between insect- and wind-pollinated flowers?
Can you describe pollination in Vallisneria?
Can you name five devices that favour cross-pollination with examples?

Pollination: frequently asked questions

Is pollen moving to another flower on the same plant cross-pollination?

No. Genetically it is self-pollination (geitonogamy), because the pollen and the egg come from the same plant. Cross-pollination needs a different plant of the same species.

Are all aquatic plants water-pollinated?

No. Many water plants, such as lotus and water lily, raise their flowers above water and are pollinated by insects. Only a few, like Vallisneria and Hydrilla, use water.

Do I need to learn bird and bat pollination?

The syllabus names insects, wind and water. Birds and bats are other agents and may appear as examples, but learn the three named ones in detail.

Why do cross-pollinated offspring tend to be stronger?

They combine characters from two different parents, which often gives greater vigour, better yield and more resistance to disease than repeated self-pollination.

Based on: CISCE ICSE 2028 Science (52) Biology (Science Paper 3) syllabus, Classes IX and X