A poppy plant of Papaver somniferum having a stably heritable thebaine-only chemotype, which plant upon the harvesting of its poppy capsules will yield a poppy straw having thebaine constituting 95% by weight or greater of an alkaloid combination, and having oripavine constituting 5% by weight or less of the alkaloid combination, wherein the alkaloid combination comprises morphine, codeine, thebaine and oripavine; and wherein thebaine constitutes 3.0% or greater of the poppy straw on a dry weight basis, wherein the thebaine-only chemotype is provided by two independent genes, the first preventing thebaine being converted to neopinone, and preventing oripavine being converted into morphinone, and the second blocking the pathway between thebaine and oripavine, wherein said plant is obtainable by i) cross-pollinating a first parent P.somniferum plant with a second parent P.somniferum plant, said first parent P.somniferum plant being a plant grown from seed of ATCC PTA-9109, and said second parent P.somniferum plant not having the thebaine-only chemotype, ii) collecting F1 seed from the cross of step (i), iii) growing an F1 plant and allowing the said F1 plants to self-pollinate, iv) collecting the F2 seed and growing an F2 population of plants from the said seed, v) selecting among the F2 population, plants which upon the harvesting of their poppy capsules will yield a poppy straw having thebaine constituting 95% by weight or greater of an alkaloid combination, and having oripavine constituting 5% by weight or less of the alkaloid combination, wherein the alkaloid combination comprises morphine, codeine, thebaine and oripavine; and wherein thebaine constitutes 3.0% or greater of the poppy straw on a dry weight basis. and wherein thebaine constitutes 3.0% or greater of the poppy straw on a dry weight basis, wherein the thebaine-only chemotype is provided by two independent genes, the first preventing thebaine being converted to neopinone, and preventing oripavine being converted into morphinone, and the second blocking the pathway between thebaine and oripavine, wherein said plant is obtainable by i) cross-pollinating a first parent P.somniferum plant with a second parent P.somniferum plant, said first parent P.somniferum plant being a plant grown from seed of ATCC PTA-9109, and said second parent P.somniferum plant not having the thebaine-only chemotype, ii) collecting F1 seed from the cross of step (i), iii) growing an F1 plant and allowing the said F1 plants to self-pollinate, iv) collecting the F2 seed and growing an F2 population of plants from the said seed, v) selecting among the F2 population, plants which upon the harvesting of their poppy capsules will yield a poppy straw having thebaine constituting 95% by weight or greater of an alkaloid combination, and having oripavine constituting 5% by weight or less of the alkaloid combination, wherein the alkaloid combination comprises morphine, codeine, thebaine and oripavine; and wherein thebaine constitutes 3.0% or greater of the poppy straw on a dry weight basis. i) cross-pollinating a first parent P.somniferum plant with a second parent P.somniferum plant, said first parent P.somniferum plant being a plant grown from seed of ATCC PTA-9109, and said second parent P.somniferum plant not having the thebaine-only chemotype, ii) collecting F1 seed from the cross of step (i), iii) growing an F1 plant and allowing the said F1 plants to self-pollinate, iv) collecting the F2 seed and growing an F2 population of plants from the said seed, v) selecting among the F2 population, plants which upon the harvesting of their poppy capsules will yield a poppy straw having thebaine constituting 95% by weight or greater of an alkaloid combination, and having oripavine constituting 5% by weight or less of the alkaloid combination, wherein the alkaloid combination comprises morphine, codeine, thebaine and oripavine; and wherein thebaine constitutes 3.0% or greater of the poppy straw on a dry weight basis.