Opium poppy (Papaver somniferum). At the centre of the flower is the stigma (yellow), part of the female reproductive organ, where pollen is deposited by insects. Underneath the stigma is the carpel (not seen), which contains the ovaries. When the flower falls off the plant, the carpel is slit, allowing a milky latex (opium) to ooze out. The latex hardens on exposure to air and can be scrapped off and formed into balls. Crude opium contains numerus alkaloids including morphine, heroin and codeine. It is used medicinally as a sedative and for pain relief. It is also used recreationally.