Question

What is the exile (in pollengrains) made up of? Why it is so rigid than other parts of the plants?

Answer 1

Exile is one of the inner coverings of the pollen-grain
It is so rigid because
1. It is composed partly of cellulose, a common component in the cell walls of plant cells.
2. The tough-as-nails outer layer is known as the exine(think exterior). This highly sophisticated and complex outer layer is rich in a compound is known as sporopollenin