Light micrograph of starch containing cells from the tuber of a living potato plant, Solanum tuberosum. Starch is a polysaccharide which occurs widely in plants as a carbohydrate energy reserve (the tubers of the potato plant are specially adapted for its storage). Consequently, starch is also important as an energy source for animals. On digestion it ultimately yields glucose. Polarised illumination. Magnification: x200 at 35mm size.