Production of thebaine and oripavine

A method to imporove the thebaine and/or oripavine yield of a stably reproducing Papaver somniferum, the method comprising the steps of:

• a) exposing at least one poppy seed of Papaver somniferum to a mutagenizing agent,
• b) growing the at least one poppy seed to produce a plant bearing a leaf or an immature poppy capsule,
• c) sampling the leaf or poppy capsule of the plant after it has reached the 10 leaf stage for the presence of thebaine, oripavine, morphine and codeine, and
• d) repeating steps a) to c) until a poppy plant of Papaver somniferum is obtained wherein the leaf or poppy capsule sampled has thebaine and oripavine constituting about 50% by weight or greater of the alkaloid combination consisting of morphine, codeine, thebaine and oripavine.