Wednesday, November 19, 2008

Pollination by insect

What is pollination?

Pollination occurs when pollen lands on the stigma of a plant. Then goes down to the ovary, and it is here that the ovules are fertilized. Most plants have flowers with male and female parts present in each flower. Most plants depend on insects as bees, to take the pollen from the anthers to the stigma.
Pollination by insects

Felt flower diagramAn insect can pollinate flowers accident, when pollen is rubbed off the body of insects. Plants can produce nectar in the flowers, a sugary liquid, as many insects living on. Pollen is a useful source of protein for some insects such as bees. Insects attracted to the flower of fragrance, color and nectar. They bear the pollen from flower to flower, while collecting nectar and pollen for themselves. After pollination, the plant produces a seed that grows mostly sheltered inside the plants' ovaries.

Click on the image above to see all the different parts of a flower.
Without insects for pollination

It is not always the insects that pollinate the flowers, plants can use wind, birds and even bats as pollinators! With wind-pollinated plants - such as grasses, grains and some trees - the flowers are very simple, with no bright colors or pleasant smells as they do not need to attract the insects. These plants have both male and female reproductive parts, and they do a lot of pollen. Therefore, a pollen allergy called 'hay fever'.
Interesting facts

* Bee pollinating a flower Most plants grow flowers annually, but some take much longer. Agave, or century plant grows only one flower after many years and then dies! Even more astonishing is a rare plant called Puya raimondii from the Andes in South America, and it does not grow a flower until it is 150 years old - and after it dies too.
* The smallest flowering plant in the world believed to be a floating duckweed called common watermeal. Its leaves are only 1 mm across!
* Bamboo flowering plants have great habits. There are many different kinds of bamboo, and they have different flowering cycles. A few flower every year, but most wait much longer. What is amazing is that all the bamboo of the same species will flower at exactly the same time they are growing! No one knows how they manage to do so.
* The flowers on the European edelweiss covered with a thick layer of hair to protect them from the hot sun and drying winds.
* The flowers from the white chalk, which can grow in Britain, are toxic to bees. They are often on the ground under the trees.
* Hummingbirds hover in front of flowers, while they collect nectar. They spend so much energy to do this, it would be like you need to eat 150kg of hamburgers every day!
* Hummingbirds use up lots of energy floating in front flowersThe white flower in the Amazon water lily is the size of a football and turning purple, after being pollinated.