The generative cell of a two celled pollen divides in the pollen tube, but not in a three-celled pollen. Give reasons.

Explanation

In over `60%` of angiosperms , pollen grain are shed at this 2-celled stage tube cell or vegetative cell generative cell. In the remaining species, the generative cell divedes mitotically to give rise to the two male gametes before pollen grains are shed tubecell or vegetative cell two male gamete 3-celled stage.
In 3 celled stage, the pollen grains further germinate on the stigma to produce pollen tube through ane of the germ pores. The contents of the pollen grains move nito the tube pollen tube grows through the tissues of the stigma and style and reaches to ovary . Inplants , when pollen grain are shed at 2 celled stage the generative cell divides and form two male gemetes during the growth of the pollen tube in the stigma.