Field poppies. Wild poppies (Papaver rhoeas) in a barley field. The flowers are bright red with the petals shading to black at the centre. Poppies are a common cornfield weed in Europe, Australia and America. Poppy seeds are very long lived in the soil (40 years) so fields must be regulally sprayed with herbicides. Poppies are annual herbaceous plants which grow to 40-70cm in height.