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

Explanation

Pollengrain, at maturity divides periclinally and produce two unequal cells. The larger cell is vegetative cell, has abundant food reserve and a large irregularly shaped nucleus. The smaller cell is generative cell and floats in the cytoplasm of vegetative cell which is spindle shaped with dense cytoplasm and a nucleus. In over `60%` of angiosperms, pollengrains are shed at this 2-celled stage. In the remaining, species, the generative cell divides mitotically to give rise to the 2 male gametes before pollengrains are shed (3 celled stage).
The pollen grain germinates on the stigma to produce a pollen tube through one of the germpores. The contents of the pollen grain moves into the pollen tube. Pollen tube grows through the tissues of the stigma and style arid reaches the ovary.
In plants, when pollen grains are shed at 2 celled stage, the generative cell divides and forms two male gametes, during the growth of the pollen tube in the stigma.