Insect Pollination

Basic's of Pollination

Plants are pollinated when pollen is placed on the stigma of a flower. This is part of the female reproductive organs which are called the Carpel. The pollen is produced on the anther which is part of the male reproductive organs which are known as the Stamen. When pollen is taken from one flowers anther and deposited on another flowers stigma we say pollination has occurred. If this process is carried out by a pollinator we call it cross-pollination. Cross pollination is better than self-pollination as it helps to maintain a wide gene pool.
Pollination is carried out so that a process known as fertilization can occur. This refers to the fussing of a male and female gamete to produce a Zygote which will develop into a new plant. This means that the male gametes contained within the pollen grain must be transported to the female gamete which is located in the embryo sac (see diagram).

After the male and female gametes have fused the integument will form a seed coat and the embryo of the new plant will form. The Zygote is described as being a diploid cell, this is because it contains and full compliment of chromosomes in its nucleus. The Gametes contain one of each homologous pair (half the chromosomes) so they are Haploid. When the double fertilization occurs with the polar cells, a triploid cell is formed, with more genetic information than it needs. These cells are therefore unable to produce a Zygote.