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© 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?
© 2009 Marshall Cavendish International (Singapore) Private Limited
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
© 2009 Marshall Cavendish International (Singapore) Private Limited
This flower has both male and female parts.
Parts of a flower
Male parts Female
parts
© 2009 Marshall Cavendish International (Singapore) Private Limited
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.
© 2009 Marshall Cavendish International (Singapore) Private Limited
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
© 2009 Marshall Cavendish International (Singapore) Private Limited
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
© 2009 Marshall Cavendish International (Singapore) Private Limited
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.
© 2009 Marshall Cavendish International (Singapore) Private Limited
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
© 2009 Marshall Cavendish International (Singapore) Private Limited
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
© 2009 Marshall Cavendish International (Singapore) Private Limited
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)
© 2009 Marshall Cavendish International (Singapore) Private Limited
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.
© 2009 Marshall Cavendish International (Singapore) Private Limited
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?
© 2009 Marshall Cavendish International (Singapore) Private Limited
Dispersal of fruits and seeds
• 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
© 2009 Marshall Cavendish International (Singapore) Private Limited
Dispersal of fruits and seeds
• 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
© 2009 Marshall Cavendish International (Singapore) Private Limited
Dispersal of fruits and seeds
• 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
Dispersal of fruits and seeds
• 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
© 2009 Marshall Cavendish International (Singapore) Private Limited
Dispersal of fruits and seeds
• Splitting open forcefullyo Some fruits split open
when ripe to shoot their seeds away.
cotton
lady’s finger
rain tree
© 2009 Marshall Cavendish International (Singapore) Private Limited
Germination
• Parts of a seed
seed leaf
baby plant
© 2009 Marshall Cavendish International (Singapore) Private Limited
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
© 2009 Marshall Cavendish International (Singapore) Private Limited
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
© 2009 Marshall Cavendish International (Singapore) Private Limited
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
© 2009 Marshall Cavendish International (Singapore) Private Limited
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
© 2009 Marshall Cavendish International (Singapore) Private Limited
Asexual Reproduction
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
© 2009 Marshall Cavendish International (Singapore) Private Limited
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
Asexual Reproduction
heliconia plant
sucker of a heliconia plant
© 2009 Marshall Cavendish International (Singapore) Private Limited
Asexual Reproduction
• 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