That old chestnut: how sweet chestnuts came to Britain

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An ancient sweet chestnut tree at Croft Castle, Herefordshire – one of the trees analysed for the project. (PHOTO: Rob Jarman)

It has long been thought that sweet chestnut trees were introduced to Britain by the Romans – a belief popularised by 18th-century writers – but new research assessing archaeobotanical samples from this period has now cast doubt on such assumptions.

Researchers from the University of Gloucestershire and Historic England, led by Rob Jarman, examined written reports as well as specimens from museum archives that had previously been identified as Roman. They found that most of these examples had been misidentified or that their dates could not be confirmed. In fact, over the course of the whole project, only one example was definitely linked with Roman Britain: peelings from approximately five sweet chestnuts that were found at a Roman farmstead in Essex. They were discovered in a deposit of food waste that also included olives, stone pine nuts, and Mediterranean fish bones, so they may have been part of a feast of exotic foods imported from the Continent. No sweet chestnut finds were shown to have been grown in Roman Britain.

One of the sweet chestnut peelings excavated at the Roman site of Great Holts Farm in Boreham, Essex. (IMAGE: Historic England)

The project team is now trying to pinpoint the timing of the sweet chestnut tree’s arrival to Britain using dendrochronological techniques, cross-dating sweet chestnut tree-ring series with established oak tree chronologies. Using this method, some of Britain’s sweet chestnut trees have been precisely dated for the first time, with the oldest dating to AD 1640. The researchers are also working on using DNA analysis of sweet chestnut trees across Britain and Ireland to identify their European ancestral source in order to determine exactly when and from where the trees first came to Britain.

This research does not only reveal the scarcity of evidence for Roman-era sweet chestnuts, though: it also highlights the importance of museum specimens. As described by Dr Zoë Hazell, Senior Palaeoecologist at Historic England, ‘The project demonstrates the research value of archaeobotanical and other environmental materials stored within archaeological archives, some of which have been 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.’

This article appeared in CA 349.

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