In the 1980s, botanists demonstrated that the flower is able to remove its pollen and its close relatives. In fact, it destroys by enzymes the pollen that did not suit it. Now, researchers at the University of Missouri have clarified how they better distinguish pollen from others. Apparently, the enzyme is stored in a pollen compartment. However, over time the compartment is removed and the enzyme is free. It seems that when pollen is not convenient, the compartment is more easily removed thanks to a protein.