Poppy straw and concentrate of poppy straw. Poppy seed is an oilseed obtained from the opium poppy ("Papaver somniferum"). Poppy straw can be a by-product of cultivation of poppy seeds. Some people choose to wear white poppies as an alternative to the red poppy. Plants such as tobacco, cannabis, opium poppy, and coca yield psychotropic chemicals. The production of illegal opium from poppy straw is limited. Morphine is biosynthesized in the opium poppy from the tetrahydroisoquinoline reticuline. It was the first active alkaloid extracted from the opium poppy. The primary source of morphine is isolation from poppy straw of the opium poppy. Use of the opium poppy antedates written history. Small biscuits soaked in poppy seed milk are served. Ingestion of codeine or food containing poppy seeds can cause false positives. They are also sold as cut flowers in flower arrangements, especially the Iceland poppy. A variety of seeds, such as pumpkin, poppy, and caraway, may be added for taste. The color of poppy seeds is important in some uses.