A food forest is a sustainable method of growing food that mimics a natural forest. It is a diverse planting of edible plants that follows the ecosystems and patterns found in nature. Food forests can have up to seven layers, including an overstory, an understory, shrubs, herbaceous plants, roots, ground cover, and vines. Food forests grow out and up, rather than in straight rows. This allows for a much greater amount and diversity of life in a single area. It also allows for greater ecosystem functions like water retention, nitrogen fixing, carbon sequestration, and pollination. A food forest offers the long-term presence of perennial plants such as fruit and nut trees, medicinal shrubs, and other plants that remain year after year, improving the soil and producing food and medicine.