Long-headed poppy an annual or overwintering weed of arable land especially cornfields and of waste places and roadsides. It has a similar distribution to the common poppy but extends further north and is more frequent in Wales. The distribution on upland areas is limited by the lack of cultivated land but it has been recorded at 1,400 ft. It is found on light, dry, sandy and gravely soils but also flourishes on heavy land. The plant can withstand drought and occurs in quite arid areas. It was considered to be comparatively rare in the early 20th century but 50 years later it had become universally common.Long-headed poppy is very variable and the size, growth habit, capsule number and flower shape of the plant are greatly modified by the environment. In open situations it forms a flat rosette of leaves. In poor or waterlogged soils plants may be small with few capsules. A white flowered form has been recorded.
