Three sisters

The three sisters are the three main agricultural crops of various Native American groups in North America: climbing beans, corn, and winter squash. While all three provide food, the beans fix nitrogen into the soil, the corn provides support for the beans, and the broad leaves of the squash suppress opportunistic plants and help to conserve water.

The Three Sisters are a showcase in additive yielding as the produce grown using this polyculture approach yields approximately 4.02 million calories per acre, whereas a monoculture of each separately yields approximately 3.44 million calories per acre at most.