Cellulose is the main chemical that forms the main structure of plants. It is the most abundant macromolecule and the most common organic compound on Earth. It is also a kind of fiber. Cellulose is a very complex carbohydrate, consisting of 3,000 or more glucose units. Cellulose was discovered by Anselme Payen in 1838. He isolated it from plant matter and determined its chemical formula.