Give information about compatible and incompatible pollen.

In nature pollination does not guarantee the transfer of the compatible or right type of pollen. Often pollen of the wrong type, either from other species or from the same plant (it is self incompatible) also land on the stigma.

The pistil has the ability to recognise the pollen, whether it is of the right type or of the wrong type.

If pollen is not of the right type the pistil accepts the pollen and promotes post-pollination events that leads to fertilisation.

If the pollen is of the wrong type the pistil rejects the pollen by preventing pollen germination. The ability of the pistil to recognise the pollen followed by its acceptance or rejection is the result of a continuous dialogues between pollen grain and the pistil. This dialogue is mediated by chemical components and protein elements and releasing various water decomposed enzymes present in it.

It is only in recent years that botanists have been able to identify some of the pollen and pistil components and the inter actions leading to the recognition, followed by acceptance or rejection. Compatible pollination, the pollen grain germinates on the stigma to produce a pollen tube through one of the germ pores.

The contents of the pollen grain move into the pollen tube.