''Papaver rhoeas'' is an annual herbaceous species of flowering plant in the poppy family, Papaveraceae. This poppy is notable as an agricultural weed and after World War I as a symbol of dead soldiers.
Before the advent of herbicides, ''P. rhoeas'' sometimes was so abundant in agricultural fields that it could be mistaken for a crop. However, the only species of Papaveraceae grown as a field crop on a large scale is ''Papaver somniferum'', the opium poppy.