Lettuce is an annual plant of the daisy family, Asteraceae. It is most often grown for leaf vegetables, but sometimes for its stem and seeds. Lettuce is most often used for salads, although it is also seen in other kinds of food, such as soups, and sandwiches. it can also be grilled. Lettuce is easily cultivated, and it requires low temperatures to prevent the plant from flowering quickly. It is a rich source of vitamins K and A.