The Three Sisters: Beans, Corn, and Squash
Native Americans planted three crops together in rows of hills. The crops were pole beans, corn, and squash. There were cultural reasons for doing this. The three plants growing together represented the circle of life, the fact that living things depend on one another. They were gifts of the Creator, and sustainers of life. The story behind it was that the spirits of three sisters could never be parted, and they manifested themselves in the three plants growing together.
Scientifically, the planting of these three plants together has benefits for all of them. The corn takes nitrogen from the soil. Bacterial colonies on the roots of the bean capture nitrogen from the air and put some into the soil. The corn supports the vines of the beans. The squash, with its sprawling vines and leaves, keep the weeds down. The closeness of the plants conserves water and prevents water loss and soil erosion.