The ability of the pistil to recognise the pollen followed by its acceptance or rejection is :

The pistil has the ability to recognize the pollen, whether it is of the right type (compatible) or of the wrong type (incompatible). If it is of the right type, the pistil accepts the pollen and promotes post-pollination events that leads to fertilization. The ability of the pistil to recognize the pollen followed by its acceptance or rejection is the result of a continuous dialogue between pollen grain and the pistil.