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Research roasts old chestnut theory

​Research by the University of Gloucestershire and Historic England has cast doubt on the evidence behind the long-standing belief that the sweet chestnut tree was introduced to Britain by the Romans.

The sweet chestnut tree, not to be confused with the horse chestnut or ‘conker’, is commonly believed to have been brought to Britain from continental Europe by the Romans – a belief first popularised by eighteenth-century writers. However, despite stories of Roman legions storing sweet chestnut nuts in their forts, this new research found no evidence of the tree having been grown in Britain during Roman times.

Working with Historic England, researchers at the University of Gloucestershire examined written reports and analysed specimens from museum archives that supposedly described sweet chestnut from the Roman period. Samples that were thought to be sweet chestnut were instead found to have been incorrectly identified or could not be confirmed as from this time period.

Only one find of sweet chestnut nuts from Roman Britain has been verified. These remains, which consist of approximately five nuts, were found at a Roman farmhouse in Essex, in a deposit of food waste that included olives, stone pine nuts and bones of Mediterranean fish – all of which appear to have come from a feast of exotic food, probably imported from continental Europe.

Research lead and University of Gloucestershire PhD student Rob Jarman, said: “Sweet chestnut is conspicuous by its scarcity in the archaeological record. The one kind of evidence we would like to find to help define when sweet chestnut first grew in Britain would be its pollen – but so far none has been definitively dated to the Roman period or earlier.”

Dr Zoë Hazell, Senior Palaeoecologist at Historic England, said: “The results of this research have national and international importance, as they have led us to re-evaluate previously-held ideas about the history of sweet chestnut in Britain, in particular concerning the role of the Romans in its introduction. The project demonstrates the research value of archaeobotanical and other environmental materials stored within archaeological archives, some of which were kept since the 1880s. As such, it is exciting to think about the untapped potential that currently sits within archives, and also how samples we recover now may be used in the future.”

Researchers at the university, working with Dr Andy Moir of Tree-Ring Services, successfully tested a new method for accurately dating sweet chestnut wood, by cross-referencing its tree rings against documented oak tree ring timelines, which are used to date shipwrecks and ancient buildings. Some of Britain’s veteran sweet chestnut trees have been accurately dated for the first time using this method.

The university’s Centre for Environmental Change and Quaternary Research is now working with the Future Trees Trust to use DNA from sweet chestnut trees across Britain and Ireland to find out where they came from – and possibly help with the timing of sweet chestnut’s arrival in Britain.

Gloucestershire has some of the most ancient sweet chestnut trees in the country – the Tortworth chestnut, near Thornbury, is thought to be 1,000 years old.

This research is one of a number of projects the university is highlighting as part of the national MadeAtUni campaign, which is designed to bring to life the difference universities make to people, lives and communities across the UK. To find out more about our research visit: