The furthest north that the Greater Water Parsnip currently grows is in the Lower Derwent Valley National Nature Reserve, to the south of York.
The Greater Water Parsnip is extremely difficult to re-establish and the Environment Agency will be monitoring the success of the trial.
The agency has been working with Natural England to reintroduce the Greater Water Parsnip on to Newham Fen.
The Greater Water Parsnip is found in wet ditches and marshes, growing in shallow, still or slow moving water.
Biodiversity experts are planning to reintroduce the rare and endangered Greater Water Parsnip to Northumberland.