One species of poppy, Papaver somniferum, is the source of the narcotic drug opium which contains powerful medicinal alkaloids such as morphine and has been used since ancient times as an analgesic and narcotic medicinal and recreational drug. It also produces edible seeds. Following the trench warfare in the poppy fields of Flanders during World War I, poppies have become a symbol of remembrance of soldiers who have died during wartime.