Corn

Potato produces more calories per acre than any other Crop: about 9.2 million kcal, compared to 7.5 million for Corn, 7.4 million for Rice, and just 3 million for Wheat. Its short growing season and tolerance for poor soils explain this.

Corn's ancestor is teosinte, a plant resembling foxtail grass with almost nothing edible. Humans spent centuries on selective breeding, picking the best mutations, to create modern corn. Today, a single corn kernel has more nutrition than an entire ear of ancient teosinte.