Anthers
Pollen grains in plants are produced in the anthers.

Explanation:
- Pollen grains are the male reproductive cells of flowering plants. They are responsible for fertilizing the female reproductive cells, known as ovules, to produce seeds.
- Anthers are the male reproductive organs of the flower. They are located at the top of the stamen, which is the male part of the flower.
- Anthers contain pollen sacs, which are small structures that produce and store pollen grains. Each pollen sac contains numerous pollen grains.
- When the flower is ready for pollination, the anthers release the pollen grains. The pollen grains are often sticky or have special structures that allow them to adhere to insects, birds, or other pollinators.
- Once the pollen grains are transferred to the female reproductive organ of another flower, such as the stigma, they can germinate and grow pollen tubes to reach the ovules and fertilize them.
- The fertilized ovules will develop into seeds, and the surrounding tissue will develop into fruits.

Summary:
Pollen grains in plants are produced in the anthers, which are the male reproductive organs of the flower. The anthers contain pollen sacs that release the pollen grains for pollination and fertilization.