Corn on the cob is the culinary term for a cooke ear of freshly-picked maize (Zea mays ssp. mays L.) from a cultivar of sweet corn. The ear is picked while the endosperm is in the "milk stage" so that the kernels are still tender. Other varieties (called field corn) are edible as "roasting ears", but are not tender or sweet. Ears of corn still in their green husks are roasted, steamed or boiled. The husk leaves are then removed before serving. Sweet corn rapidly loses its sugars after picking as they are converted to starch, so it is important to cook the ears as soon as possible after picking.