Outline the events that lead to the formation of pollen grains in flowering plants.

This question requires that you describe what happens in the anthers during formation of pollen grains from the meristematic cells to mature pollen grains. However, you should start by indication where in the plant, this process occurs.

Pollen grains are formed from meristematic cells in pollen sacs of the anthers.

In infancy, each pollen sac consists of a homogenous mass of meristematic cells.

During development, these cells differentiate into four layers of cells. The central layer called the sporogenous layer divides to produce a number of microspores, also called pollen mother cells.

Pollen mother cells divide by meiosis and each produces four haploid cells.

Each haploid cell develops a tough productive wall around itself and becomes a pollen grain.

Complete maturation involves mitotic division of the haploid nucleus inside the pollen grain to form two haploid nuclei of unequal size. The larger is called the generative nucleus and smaller is the pollen tube nucleus.