Lettuce is an annual plant of the daisy family, Asteraceae. It is most often grown as a leaf vegetable, 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, sandwiches and wraps; it can also be grilled.
 
Shelf Life: one to three weeks Loose leaves can last seven to 10 days when properly stored, but head lettuce lasts much longer than that. Left intact and unwashed, head lettuce, like romaine or iceberg, will last one to three weeks in the fridge. Just cut off the ends and store them in the crisper drawer with paper towels to absorb moisture.