Potato roots. Roots of a potato plant (Solanum tuberosum), dug up and washed to show the edible parts of the potato (the tubers) at bottom. Around them, a branching network of roots (white) obtained water and mineral nutrients from the soil. Protruding above the soil are the stalks and leaves (green), which contain chlorophyll (a green pigment) that uses the energy in sunlight to form sugars from water and carbon dioxide (a process called photosynthesis).