Potato roots. Cutaway view of the parts of a potato plant (Solanum tuberosum) growing in soil. The edible part of the potato (the tuber) is seen at centre, mostly obscured by the soil. Around it, a branching network of roots (white) obtain water and mineral nutrients from the soil. Protruding above the soil are the stalks and leaves (green) that contain chlorophyll (a green pigment) that uses the energy in sunlight to form sugars from water and carbon dioxide (a process called photosynthesis).