 Lettuce ( Lactuca sativa ) 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 was first cultivated by the ancient Egyptians who turned it from a weed , whose seeds were used to produce oil , into a food plant grown for its succulent leaves , in addition to its oil @-@ rich seeds . Lettuce spread to the Greeks and Romans , the latter of whom gave it the name lactuca , from which the English lettuce is ultimately derived . By 50 AD , multiple types were described , and lettuce appeared often in medieval writings , including several herbals . The 16th through 18th centuries saw the development of many varieties in Europe , and by the mid @-@ 18th century cultivars were described that can still be found in gardens . Europe and North America originally dominated the market for lettuce , but by the late 20th century the consumption of lettuce had spread throughout the world . 
