A tiny rare violet has been rediscovered at Britain's oldest nature reserve after an absence of a decade, the National Trust has said.
The fen violet (Viola persicifolia), which has blueish-white flowers with a mother-of-pearl sheen and grows to a maximum of little over an inch (25-30mm), is known to exist at only three sites in the wild in the UK.
One of these is Wicken Fen, Cambridgeshire, where it had not been seen since 2003 but was rediscovered during a botanical survey this week.
Seeds of the plant, which likes a wetland habitat with alkaline water, can lie dormant in the ground for many years and will only grow when the ground has been disturbed and it has the right weather conditions.
S ince the 1990s, it has only been found at Wicken Fen National Nature Reserve , Woodwalton Fen National Nature Reserve in Cambridgeshire and Otmoor Site of Special Scientific Interest near Oxford.
The violet was first recorded at Wicken Fen in 1860, and was rediscovered in the 1980s having vanished for 30 years.
It disappeared again from its stronghold in the fen at the turn of the century, and a small number which had been transplanted to a new area were last seen in 2003.
National Trust countryside manager Martin Lester said: "It was a moment of satisfaction, surprise, tinged with relief that we had found it again.
"This delicate wetland plant is clinging on to survival not just in this country but across Europe. No-one can really explain why it can disappear for long periods only to reappear decades later - let's hope it says around for a few years this time."
Wicken Fen is home to many rare plant species including the marsh pea, the marsh fern, the milk parsley and the whorled water milfoil, as well as a number of different orchids.
The site is part of the Wicken Fen Vision - a 100-year project by the National Trust to create a 13,000 acre nature reserve stretching from the fen to the outskirts of Cambridge.
Mr Lester said the return of the fen violet "cements the important role Wicken Fen and the Wicken Fen Vision project has in international conservation, protecting and creating new habitats for endangered species".