Mexican prickly poppy (Argemone mexicana) belongs to the Papaveraceae (the Poppy family). It is an annual herb that is native to Mexico, and now widely naturalized in the United States, India and Ethiopia. This herb grows in sunny grasslands, and can reach 30-60 cm in height. The leaves are prickly and thistle like. The yellow flowers bloom from June to August. The bright yellow saps ooze when the stems or leaves are injured. The seeds contain non-edible oil, called argemone oil, which contains the toxic alkaloids sanguinarine and dihydrosanguinarine.