By Aditi Atmasidha

Flowers are reproductive structure of a plant. It contains

reproductive organs like Androecium

{ male organ } and Gynoecium { female organ }.

Some flowers are bisexual that is both reproductive organs are present on the same flower.

{ Example: Rose }

Some flowers are unisexual that is reproductive organs are present on different flowers

{ Example: Pine }

The transfer of pollen grains from Androecium to Gynoecium is called Pollination .

Introduction

Pollen grains are small particles which are involved

in reproduction of flowering plants.

They act like male gamete { sperm cells } and helps in producing a seed that further grows in a plant.

This process of reproduction in plants is called pollination which is done with the help of pollen grains.

What are pollen Grains ?

There are many different types of pollen grains,

some have spikes while others are light. Pollen grains with spikes are easily carried by insects and animals.

Pollen grains which travel due to wind are light in weight and can easily e lifted by the wind.

Pollen Grains

Pollination is the process by which pollen is

transferred from the anther to the stigma of the Plant, thereby enabling fertilization and reproduction. This takes place in the angiosperms, the flower bearing plants. { Plants that produce flowers & fruits }

There are two types of pollination: Self And cross Pollination.

Pollination

Cross Pollination Self Pollination

Cross pollination is the transfer of pollen grains from the anther of a flower to the stigma of a flower of a different plant of the same species.

Self pollination is the transfer of pollen grains from the anther to the stigma of the same flower

Insects: Apples, grapes, plums, pears, raspberries, blackberries, strawberries, runner beans, pumpkins, daffodils, tulips, lavender Wind: grasses, catkins, dandelions, maple trees, and goat’s beard.

Seen in peanuts. Orchids, peas and sunflowers, wheat, barley, oats, rice, tomatoes, potatoes, apricots and peaches.

Types of pollination

Means of Pollination

Organs involved in Pollination

Flowers release pollen from anthers before stigmas

of the same flower are ready to receive it.

Stigmas of the flower are ready to receive pollen from other plants of the same species before its own anthers are ready to release pollen.

Ways to avoid self pollination

The bird of paradise flower has stamens that form

perches for birds. They pick up the pollen on their feet.

The flowers of the century plant contain large amounts of nectar for bats to drink. The bat carries away pollen on the fur on its head and neck.

Honeysuckle flowers produce nectar at night to attract moths to pollinate them.

Unusual methods of Pollination

Canadian pondweed produces male and female

flowers on long stocks which reach the water surface, the male flower releases pollen on to the water and it floats away, some of the pollen reach the female flower and pollination occurs.

The cuckoopint has male and female flowers on short stem covered by hood { cap structure }.

The plant releases an unpleasant smell to attract small flies. Flies enter the hood by pushing downward pointing hairs. As they pass over female flowers the stigmas collect pollen from the insects.

Unusual methods of Pollination

The hairs prevent the insects from leaving for few

days. During this time male flowers make pollen. When male flowers release pollen the hair of insects wither so that they can crawl and collect the pollen again.

Rafflesia is a parasitic plant that lives on the roots of the vines in the Malaysian rainforests. It produces largest flowers with circumference of 91 cm. It spreads the smell of rotting meat to attract flies for process of pollination. The male and female flowers are separate.

Unusual methods of Pollination

The scent of nectar producing flower travels through

the air, it ensures that the receptor cells of honey bees get attracted towards it. The bees also use their eyes to find the flower. Its eyes are sensitive to ultra-violate and help the bee to identify the flower.

It also directs the bees towards the nectar. When a bee lands on a flower it sticks its head between the stamens and sip the nectar with its mouth. While taking up the nectar it brush pass the anthers and collect pollen on the hair of its back.

Bees & Pollination ?

When a bee settles on other flower some of the

pollen on its back passes on the stigma of next flower. The bee has stiff hair on its front legs which act like a comb as collect the pollen off the bees backs and is stored in structures called pollen baskets which are made from hair on its back legs.

The action of enzymes and addition of other substances change the nectar into honey. When the bees returns to their hives, it regurgitates the honey and passes it to other bees in the hive and atlast the honey is stored in the hives.

Bees & Pollination ?

Also the pollen is removed from pollen baskets and

stored.

A bee indicates the source of nectar to other bees in the hive by performing movement on the honey comb. The movement is as follows: moving in circles, waggling its abdomen, moving up and down on the vertical surface of honey comb. This movement enables other bees to find distance, direction and amount of nectar available.

Bees & Pollination ?

Bees & Pollination ?

http://www.youtube.com/watch?v=dgFY7WUTAS

Q

http://www.youtube.com/watch?v=bwCpQflmQG4

Fertilization & Fruits

Plants Carriers of Dispersal Ways of Dispersing

Oak & Brazil nut Squirrels and mice carry it.

Dropping fruit on ground.

Brazil nut Agouti { rat like mammal }

Take away from thetree at long distance.

Goose grass & Burdock Mammals Hooks on fruits, stick to the fur of passing mammal.

Willow Herb & Dandelion

Wind Hair on the fruit of these plants.

Sycamore [ Maple tree]& Tipu tree

Wind Winged fruits carried by wind.

Berries Animals & Birds Seeds are excreted through faeces.

Dispersing Fruits & Seeds

Apricot Animals Flesh is eaten and seed

is thrown away.

Lupin & Gorse Dry pods twist and split to release seeds.

Dispersing Fruits & Seeds