Question

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

Answer 1

Requirement for double fertilisation

The process of double fertilisation can take place only when two male gametes are released into the embryo sac. These male gametes are formed by the mitotic division of the generative nucleus found in the pollen grain.

2 celled pollen grain

Usually the pollen grain is shed at the two celled stage. A two-celled mature pollen consists of one vegetative cell and one generative cell. It forms the pollen tube, when it lands on the stigma of another flower.
The generative cell then divides in the pollen tube to produce two male gametes for the execution of double fertilisation.


3 celled pollen grain

In some species, pollen grains are shed off at the 3 celled stage. The pollen grain contains one vegetative cell and two male gametes. The male gametes are formed by the mitotic division of the generative cell.
As two male gametes are already present for double fertilisation, generative cells don't divide in the pollen tube.