© 2009 Marshall Cavendish International (Singapore) Private Limited.

© 2009 Marshall Cavendish International (Singapore) Private Limited

Questions to think about…

What are the parts of a flower?

How do flowering plants

reproduce?

How do non-flowering plants reproduce?


Reproduction in flowering plants

• Flowering plants can reproduce from seeds.

• To reproduce, plants produce flowers which develop into fruits and seeds.

• For fruits and seeds to be produced, the flowers must be pollinated and fertilised.

a tomato seed


This flower has both male and female parts.

Parts of a flower

Male parts Female

parts


Parts of a flower

• The male parts of the flower are the anther and filament. o The anther contains pollen sacs which produce pollen

grains.

• The female parts of the flower are the stigma, style, ovary and ovule.


Parts of a flower

• Some plants like the papaya have the male and female parts in separate flowers.

male flower of the papaya plant

female flower of the papaya plant


Pollination

• Pollination is the transfer of pollen grains from the anther to the stigma of a flower.o The pollen grains can be transferred within

the same flower.

stigma pollen grains from anther


Pollination

• Pollination is the transfer of pollen grains from the anther to the stigma of a flower.o The pollen grains can also be transferred from

one flower to another.


Fertilisation

• When a pollen grain lands on the surface of a stigma, it produces a tube.

• The inside of the tip of the tube contains the male cells of the flower.

• These tubes grow down the style to reach the ovules in the ovary.

• Inside each ovule is an egg cell.

pollen grainsstigma

pollen tubes style

ovary

ovuleegg cell


Fertilisation

• When a pollen tube reaches the ovule, the female egg cell and male cell combine.

• This process is called fertilisation.

yellow pollen grains on a flower


From flower to fruit

After fertilisation, most of the flower parts wither and drop off

except for the ovary.

Inside the ovary, the ovules begin to

develop into seeds.

The ovary then grows bigger until it becomes

a fruit.

seeds develop inside the fruit, fruit grows bigger

petals drop off

ovary begins to swell

petals wither

flower (after fertilisation)


From flower to fruit

• Sexual reproduction involves a male and a female.

• The process of producing new plants from seeds involves both male and female cells.

• Thus, sexual reproduction takes place in plants.


Dispersal of fruits and seeds

In order for seeds to grow at a suitable

place, they must be scattered.

Why is that so?

Well, if the seeds grow too closely together,

overcrowding might occur. I see! So if this happens, the young plants may not

get enough water, minerals and sunlight to

grow well.

That’s right. Also, some fruits are scattered while the seeds remain inside them. The scattering of seeds or fruits is called

dispersal.

So what are the ways in which fruits and seeds are

dispersed?



• Windo Fruits and seeds dispersed

by wind are often dry and light.

o Some of them have wing-like structures.

o They are easily carried by wind.

lalang

angsana

dandelion



• Animalso Some fruits can be eaten by animals.o Their seeds are thrown away or passed out in

the animals’ droppings if swallowed.

kiwi

papayawatermelon



• Animalso Other fruits and seeds attach themselves to

animals’ bodies or our clothes by using hooks or stiff hairs.

mimosalovegrass © 2009 Marshall Cavendish International (Singapore) Private Limited


• Watero Fruits dispersed by water usually float and are

carried along rivers, streams or at sea.o They often have waterproof coverings or fibrous

husks to help them float in water.

coconut lotus plant mangrove



• Splitting open forcefullyo Some fruits split open

when ripe to shoot their seeds away.

cotton

lady’s finger

rain tree


Germination

• Parts of a seed

seed leaf

baby plant


Germination

baby plant

A seed starts to germinate when it

lands on a place with enough warmth and

water.

ripe fruit and seeds

disperse

seed

germinatesPhoto of tomato seedling, p. 48, P5A

young plant

leaves

shoot

root

First, the root of the baby plant grows out of the

seed to form a seedling.

seedling

During this stage, the seedling cannot make its own food, but gets it energy from the food

stored in its seed leaves.

Next, the shoot appears and the first leaves unfold. The young plant is now able to

make its own food.

grows


Germination

The young plant develops into an adult

plant.

ripe fruit and seeds

disperse

seed

germinatesPhoto of tomato seedling

young plant

leaves

shoot

root

seedling

grows

develops into

adult plant with flowers

When the flower of an adult plant gets pollinated and

fertilised, the cycle of reproduction repeats itself.

pollination and fertilisation occurs


Non-flowering plantsNon-flowering plants• While flowering plants

reproduce from seeds, non-flowering plants reproduce in other ways.

• Sporeso For example, ferns

reproduce from spores, and do not produce seeds like flowering plants.

spore bag of a fern

ferns


Asexual Reproduction

• Underground stems o The potato is an example of an

underground stem. o It can be identified as a stem

because of the buds and leaf scars.

o The buds can grow into new plants when the potato in buried in soil.

To grow a potato plant from a cut piece of potato, each piece must contain at least

one bud.

bud shoot

A potato



water chestnut

bud

scale leaf

onion

shoot

fleshy leaf

bud

stem

root

• Underground stemso More examples:

ginger

scale leaf

bud

root

buds growing into new shoots

underground stem


sucker of a banana plant on the ground

• Suckerso Plants like banana and

pineapple reproduce by developing upright shoots called suckers.

o These shoots develop from a certain part of the stem.

pineapple plant

suckersealing

wax palm

sucker of a sealing wax palm


heliconia plant

sucker of a heliconia plant



• The leaves of plants like the bryophyllum, begonia, and African violet can produce new plants.

• Such leaves are often thick and fleshy.

leaf of new plant

root of new plant

bryophyllum leafbryophyllum

plant© 2009 Marshall Cavendish International (Singapore) Private Limited


© 2009 Marshall Cavendish International (Singapore) Private Limited.

Documents

seeds water o fruits

seeds wind o fruits

flower male parts female

seeds animals o

dispersal of fruits

flower parts wither

scattering of seeds

papaya plant female