Final answer:
Pollen grains are produced in the anthers of flowers, which are part of the stamen, the male reproductive structure.
Step-by-step explanation:
Pollen grains are produced in the anthers of flowering plants. The anther is part of the stamen, which is the male reproductive structure of the flower. Within the anther, meiosis occurs to form the male gametes or pollen grains. The filament supports the anther, positioning it to effectively disperse pollen. After production, these pollen grains can be transferred to the stigma of the same or different flower, leading to fertilization.