Any plant of the genus Papaver, family Papaveraceae, that bears brightly colored, often dark-centered, flowers and yields a milky sap. Species include the crimson European field poppy P. rhoeas and the Asian opium poppies. Closely related are the California poppy Eschscholtzia californica and the yellow horned or sea poppy Glaucium flavum.Annual or biennial or perennial herbs having showy flowers.