Papaver rhoeas (common names include corn poppy, corn rose, field poppy, Flanders poppy, red poppy, red weed, coquelicot, and, due to its odour, which is said to cause them, as headache and headwark) is a herbaceous species of flowering plant in the poppy family, Papaveraceae. This poppy, a native of Europe, is notable as an agricultural weed (hence the "corn" and "field") and as a symbol of fallen soldiers.
P. rhoeas sometimes is so abundant in agricultural fields that it may be mistaken for a crop. The only species of Papaveraceae grown as a field crop on a large scale is Papaver somniferum, the opium poppy.
Apaver rhoeas is a variable, erect annual, forming a long-lived soil seed bank that can germinate when the soil is disturbed. In the northern hemisphere it generally flowers in late spring, but if the weather is warm enough other flowers frequently appear at the beginning of autumn. It grows up to about 70cm in height. The flowers are large and showy, 50 to 100mm across, with four petals that are vivid red, most commonly with a black spot at their base. The flower stem is usually covered with coarse hairs that are held at right angles to the surface, helping to distinguish it from Papaver dubium in which the hairs are more usually appressed. The capsules are hairless, obovoid in shape, less than twice as tall as they are wide, with a stigma at least as wide as the capsule. Like many other species of Papaver, the plant exudes white to yellowish latex when the tissues are broken.