Sweet corn (Zea mays convar. saccharata var. rugosa; also called sweetcorn, sugar corn and pole corn) is a cereal with a high sugar content. Unlike field corn varieties, which are harvested when the kernels are dry and mature (dent stage), sweet corn is picked when immature (milk stage) and prepared and eaten as a vegetable, rather than a grain. Since the process of maturation involves converting sugar to starch, sweet corn stores poorly and must be eaten fresh, canned, or frozen, before the kernels become tough and starchy.