The spread of large-scale cultivation and consumption in eastern North America occurred around 900 AD. It was grown along with beans and squash on hillsides by Native Americans in a complex system known as the "Three Sisters."
Corn provided support for the beans, and the beans provided nitrogen from nitrogen-fixing rhizobia bacteria that live on the roots of beans and other legumes. "The third sister" was squash, which covered the ground, preventing weed growth and also inhibited evaporation by providing shade to the soil.
