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RBG, Kew: Guidance on Corn Cockle

Monique Simmonds, Head of RBG, Kew’s Sustainable Uses of Plants Group says:

'This plant, like many we have in our gardens, does contain compounds that can be toxic if eaten in large amounts or eaten frequently over a period of time. The toxic compounds are in higher concentrations in the seeds, which are hard and very bitter. If eaten by a child, the child would most likely be sick or complain of a stomach ache. There is no evidence that eating a few seeds would cause acute toxicity.

'In the past, problems associated with toxicity occurred in Europe when flour contaminated by corn cockle seeds was consumed in bread, and this contaminated bread was eaten over a period of time. The fact that there are very few reports about any form of toxicity to humans in other parts of Europe, where the plants are more common, indicates that although toxic, the plant is not considered a high risk.'

‘People may be interested in Kew’s Autumn festival this year which explores how potential lethal plants, have been used in life changing and life saving medicines. E.g. the Yew tree, foxglove etc, and gives us a new understanding of how modern medicine is largely underpinned by the botanical world.’ 

Additional information from the RHS

Guy Barter, the Chief Horticultural Advisor to the RHS, says:

'Like many garden plants, corn cockle (officially called Agrostemma githago) is potentially harmful, especially if consumed. Merely touching this plant is a very low risk indeed. We know of no instances of harm occurring from this plant in gardens, but in historical times cases of poisoning occurred from consuming contaminated bread. Modern agricultural practices have eliminated it from farm crops.

'Like other potentially harmful garden plants the actual risk of harm is extremely small as a considerable amount of a very acrid (bitter) plant would have to be consumed to cause ill-effect. The usual sensible garden precautions should be  followed; refrain from eating any plant not known to be edible, wash hands after working in the garden and before eating or touching lips and eyes, and see that pets and children who cannot be entirely trusted not to consume vegetation are supervised. If these simple precautions are followed there is no reason not to grow this plant. Corn cockle is a very rare wildflower, but contrary to recent reports has never actually become extinct in Britain merely hanging on in a very few isolated pockets.

'Cultivated seed of this plant has been widely sold as a "wildflower" and consequently it is not uncommon in gardens.  It is a corn field annual, so it can only grow on disturbed ground. Therefore, it generally has to be sown afresh each year or the ground disturbed to produce its preferred conditions where seed is already present in the soil.'


For more information, please contact the RBG, Kew Press Office on:

Tel: 0208 332 5607