Although monocots and eudicots differ in their arrangement of floral organs, all angiosperms use flowers to facilitate pollination. The goal of pollination is to transfer pollen which is made in the to the of another flower where two sperm are released and travel to fertilize the egg and central cell. *

Pollen sac of anther, stigma.

Explanation:

Pollen is synthesized inside the pollen sac of an anther.  An anther is a part of male reproductive organ in plants which has many pollen sacs. In order for the pollen grain to fertilize an egg cell and central cell, it must reach the stigma of ovary. Once the pollen which has two sperm nuclei reaches the stigma, it starts growing and develops pollen tube so as to reach the embryo sac. Embryo sac contains 7 cells and 8 nuclei. It has 3 antipodal cells at the chalazal end, 1 central cell with 2 nuclei at center and at micropylar end it has 3 cells out of which two are synergids and 1 is egg cell which is situated in between synergids. One of the sperm nuclei fuses with central cell and another one fuses with egg cell as a result of this fusion, the central cell now has 3 nuclei while egg cell has 2 nuclei. The process of fusion of sperm nuclei with central cell is known as triple fusion and the structure later on develops into endosperm. The fusion of 1 sperm nuclei with egg cell produces zygote which later develops into an embryo. The formation of these two structures is known as double fertilization.