Pollen grains in wheat are shed at 3-celled stage while in peas they are shed at 2-celled stage. Explain. Where are germ pores in a pollen grain?

In plants like peas, the microspores have two cells: vegetative and generative. The vegetative cell has abundant reserve food material and a large nucleus which is irregular in shape, while the generative cell is spindle-shaped. These are shed at the two-celled stage. While in plants like wheat, the generative cell divides mitotically and gives rise to two male gametes before pollen grains are shed at the three-celled stage.