Coca
Coca has been cultivated by Andean cultures for thousands of years. Traditionally people would chew the leaf or soak it in hot water to make tea in order to get a small energy boost. Coca was introduced to Europe in the 16th century. After its stimulating effects were described by a European doctor in the 19th century, people began to refine the leaves to get cocaine. As people began to learn more about cocaine it began to be banned in many countries. In 1961 the United Nations classified the coca leaf as a narcotic even though studies had shown the leaf itself was non-addictive. This has led the United States to pressure coca-growing countries such as Peru and Bolivia to stop growing coca entirely. These countries have responded by fighting the 1961 decision, trying to remove the coca plant from the list.