Transcript SAPS - Pollination

 J. and A. Bebbington 2004
This presentation may be used only by
recognised educational institutions
POLLINATION
1
stigma
stamen
In flowering plants, pollination is the carrying of pollen
from the stamens (male part of the flower)
to the stigma (on the female part of the of flower).
2
On the stigma
the pollen grain
grows a
pollen tube
down the style
into the ovary.
Fertilisation
takes place when
the pollen tube
and the ovule
come together.
stigma
POLLINATION
style
stamen
ovary
FERTILISATION
ovule
After fertilisation the ovule develops into a seed.
3
Bee orchid
Sweet Vernal-grass
There is an
enormous
variety in the
size, colour
shape and even
smell of
flowers.
This is related
to the way in
which they are
pollinated.
4
Marsh-marigold
Honeysuckle
bright red
stigmas
of female
flowers
male
flowers in
catkins
In Britain pollen is usually carried either by wind or insects.
Wind-pollinated flowers, like the male Hazel flowers shown
here, are often small, and borne in long dangly catkins.
These are blown about by the wind, releasing large amounts
of pollen.
5
Here a hazel catkin
shows the large amount
of pollen shaken out of
it as it moves.
Pollen being blown
around in the wind may
not find a stigma and
will be wasted.
Wind-pollinated plants
produce a lot of pollen
and this increases the
chance of success.
6
feathery stigma which
sweeps pollen from the air
stamens with long
dangling stalks
In June and July, it is often the grasses, releasing
very large amounts of pollen, which cause problems for
hay fever sufferers
7
spur containing
nectar
Insects visit flowers to find food, e.g. nectar.
In the Butterfly-orchid nectar is stored in a long
tube (the spur) which is part of the petal.
8
Many insects
feed on pollen.
This bee is
collecting
pollen in its
pollen basket
to feed to its
larvae.
pollen basket
9
As an insect
moves from
flower to
flower, pollen
stuck to its
body has a
good chance
of landing on
a stigma.
pollen
10
The next few
pictures show you
a few examples of
how flowers, like
the Foxglove
shown here, are
adapted to their
pollinating insects
11
The Foxglove
flower is just
the right size
for a bumblebee
to fit inside.
bee going into foxglove
12
stamen
As the bee
squeezes into
the Foxglove
flower its back
brushes against
the stamens and
stigma.
stigma
hairs
Smaller insects
can’t enter the
flower because
of the long
hairs at the
entrance.
13
The Evening
Primrose is
pollinated by
moths flying
in the
evening.
The luminous yellow petals are easily seen in the dusk.
Sticky chains of pollen cling to the visiting moths.
14
Broom is designed to be
pollinated by heavy
insects like bees.
The male and female
parts are all tightly
packed into the keel.
wing
wing
keel
When a heavy insect
lands on the wings, they
are pushed downwards
and the bee hits the
keel, which then
explodes!
15
The stamens,
style and stigma
whizz round the
insect both
collecting and
covering it with
pollen.
16
Most insect-pollinated flowers are large and brightly
coloured so that insects can easily find them.
If they are small they may be grouped together to
look like a large flower as in this Dandelion.
17
Can you think why not many British wild flowers are red?
18
Many insects do
not see red well,
so it would not
be a good colour
to use to attract
them.
19