Papaya (Carica papaya) is also often called melon tree or papaya tree. It originates from coastal regions of South America, but has been cultivated over the years in wide tropical and subtropical parts of the world. Only in Mexico and Costa Rica does it grow in the wild today. The small black seeds of the papaya contain a large amount of papain. Papain is a protein-splitting enzyme that is used as an aid in the food industry.