Lettuce (Lactuca sativia) is an edible leaf plant from the Asteraceae family of plants. The earliest known cultivated lettuce was grown in ancient Egypt. The Egyptians cultivated and hybridized local edible weeds that eventually grew into lettuce we would recognize today. They prized lettuce for its oil-rich seeds, which were pressed to extra oils for cooking. They also enjoyed salads much the same as we do today and used lettuce in soups, stews and for cooking. Lettuce is easily grown in most climates, although it prefers cooler temperatures. It is a rich source of vitamins A and K.