Fertilisation of flowers
Flowering plants generate pollen in the anther. The anthers split open and release the pollen grains. The pollen grains are transferred to the stigma of another similar flower by various means such as insects or wind. After the pollen lands on the sticky stigma the pollen grains germinate and a pollen tube (with the nucleus of the pollen) passes down through the style and into the ovary to fertilise the egg.
The pollinator brings the pollen from the anthers of flower A to the stigma of flower B.
Some plants self-pollinate.