Glaucium flavum, the yellow horned poppy, yellow hornpoppy or sea poppy, is a summer flowering plant in the family Papaveraceae. It is native to Europe, Northern Africa, Macaronesia and temperate zones in Western Asia. The plant grows on the seashore and is never found inland. All parts of the plant, including the seeds, are toxic. It is classed as a noxious weed in some areas of North America, where it is an introduced species. It is grown in gardens as a short-lived perennial but usually grown as a biennial.
It has thick, leathery deeply segmented, wavy, bluish-grey leaves, which are coated in a layer of water-retaining wax. The sepal, petals and stamen have a similar structure and form to the red poppy (Papaver rhoeas), except the sepals are not hairy. It grows up to 30–90 cm (1–3 ft) tall,[4] on branched, grey stems. It blooms in summer,[5] between June and October. It has bright yellow or orange flowers,[5] that are 7.5 cm (3 in) across. Later it produces a very long, upright, thin, distinctive horn shaped capsule, which is 15–30 cm (6–12 in) long. It is divided into two chambers, which split open to reveal the seeds.
