Corn cockle is a softly hairy, waist-height annual plant, with large pink-purple flowers that produces capsules containing large seeds. All parts of the plant are toxic, principally due to the presence of triterpensaponins (gypsogenin).
For at least 4,000 years this distinctive species has been associated with European agricultural landscapes; the generic name means 'garland of fields'. Glasshouse studies have shown that wheat plants grown in the presence of corn cockle produces more leaves, stems and grain than wheat plants grown alone.
For most European agriculture during this time, grain was probably contaminated with corn cockle seeds causing problems for millers and consumers. The problem was propagated into subsequent years with the practice of saving grain from one year to the next. Consequently, corn cockle was often a troublesome weed, and frequently blamed for mass poisonings of rural populations. One of its common names (hell corn), used during the Middle Ages, probably reflects such events. An alternative explanation is that the crop was contaminated with the sclerotia of the ergot fungus (Claviceps purpurea), which contains derivatives of LSD, and used to be a frequent contaminant of rye.
Corn cockle was common in sixteenth-century Europe, with the herbalist John Gerard stating that 'what hurt it doth among corne, the spoyle unto bread, as well in colour, taste, and unwholesomnes, is better known than desired'. Some writers have been more mindful of corn cockle as 'an ornament of our fields'. During the nineteenth century, people started to notice the disappearance of corn cockle in England and by the end of twentieth century this was a widespread European phenomenon.
Arable weeds in general are not species one would typically imagine as conservation icons. As formerly common species that probably evolved with us during our 10,000 year-long adventure with agriculture, they might be expected to acclimate readily to environmental change.
Factors responsible for arable weed disappearance are associated with the mechanisation of agriculture, improvements in seed cleaning processes and the use of herbicides and fertilisers. For the farmer, concerned with food production, the disappearance of arable weeds is a boon. For the environmentalist, arable weed decline is symptomatic of wider environmental problems. Despite the concern over corn cockle in Europe, the species does not face global extinction. It remains a significant problem of agriculture in other parts of the world, where European concerns over its decline must seem like an indulgence of the well fed.
Sogaard B and Doll, H 1992. A positive allelopathic effect of corn cockle, Agrostemma githago, on wheat, Triticum aestivum. Canadian Journal of Botany 70: 1916-1918.
Storkey J et al. 2012. The impact of agricultural intensifiifcation and land-use change on the European arable flora. Proceedings of the Royal Society B 279: 1421-1429.
Thompson PA 1973. Effects of cultivation on the germination character of the corn cockle (Agrostemma githago L.). Annals of Botany 37: 133-154.