Most food staples are inexpensive, plant-based foods, usually full of calories for energy. There are more than 50,000 edible plants in the world, but just 15 of them provide 90 percent of the world’s food energy intake. Rice, corn, and wheat make up two-thirds of this. Food staples traditionally depend on what plants are native to a region. Rice is a food staple for more than 3.5 billion people around the world, particularly in Asia, Latin America, and parts of Africa. Rice has been cultivated in Asia for thousands of years. Scientists believe people first domesticated rice in India or Southeast Asia. Rice arrived in Japan in about 3,000 years ago. The Portuguese most likely introduced it into South America in the 16th century. Today, the world’s largest rice producers are China, India, and Indonesia. Outside of Asia, Brazil is the largest rice producer. Corn is native to Central America, where it was domesticated by the Aztecs and Mayans. The United States is the world’s largest corn grower, producing more than 40 percent of the world’s corn. Corn is often used to produce corn oil, sweeteners such as corn syrup, and cornstarch, which is used as a sweetener and thickening agent in home cooking. Also, alcohol from fermented corn is the source of bourbon whiskey. Wheat was first domesticated in the Middle East. Wheat grows well in temperate climates, even those with a short growing season. Today, China, India, the United States, Russia, and France are among the largest wheat producers in the world. The majority of breads are made with wheat flour. Wheat flour is also used in pasta, pastries, crackers, breakfast cereals, and noodles. In addition to cereal grains, roots, and tubers are common food staples, particularly in tropical regions. Yams are an important food in the rainforests of West Africa. Potatoes are native to the cold climate of the Andes Mountains. They were introduced to Europe by explorers of the 16th century and are now a food staple in Europe and parts of the Americas.