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POLLINATION

J. and A. Bebbington 2004This presentation may be used only byrecognised educational institutions

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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).

stamen

stigma

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After fertilisation the ovule develops into a seed.

On the stigma the pollen grain grows a pollen tubedown the style into the ovary.

Fertilisationtakes place when the pollen tube and the ovule come together.

POLLINATION

FERTILISATION

stamen

stigma

style

ovary

ovule

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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.

Bee orchid

Marsh-marigold

Sweet Vernal-grass

Honeysuckle

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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.

bright red stigmasof female flowers

male flowers in catkins

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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.

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In June and July, it is often the grasses, releasing very large amounts of pollen, which cause problems for hay fever sufferers

feathery stigma which sweeps pollen from the air

stamens with long dangling stalks

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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.

spur containing nectar

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Many insects feed on pollen.

This bee is collecting pollen in its pollen basket to feed to its larvae.

pollen basket

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As an insect moves from flower to flower, pollen stuck to its body has a good chance of landing on a stigma.

pollen

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The next few pictures show you a few examples of how flowers, like the Foxglove shown here, are adapted to their pollinating insects

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bee going into foxglove

The Foxglove flower is just the right size for a bumblebee to fit inside.

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As the bee squeezes into the Foxglove flower its back brushes against the stamens and stigma.

Smaller insects can’t enter the flower because of the long hairs at the entrance.hairs

stigma

stamen

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The luminous yellow petals are easily seen in the dusk. Sticky chains of pollen cling to the visiting moths.

The Evening Primrose is pollinated by moths flying in the evening.

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wing

keel

wing

Broom is designed to be pollinated by heavy insects like bees.

The male and female parts are all tightly packed into the keel.

When a heavy insect lands on the wings, they are pushed downwards and the bee hits the keel, which then explodes!

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The stamens, style and stigma whizz round the insect both collecting and covering it with pollen.

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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.

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Can you think why not many British wild flowers are red?

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Many insects do not see red well, so it would not be a good colour to use to attract them.

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