A collection of more than 200 samples of wild plants spanning more than 40 years has been stolen from the car of a wildlife expert.

Brian Eversham’s Toyota Prius was parked at Thetford Warren lodge, off Brandon Road, near Brandon, on December 10 when the rear window was smashed.

Two plastic drawers containing samples of lichens, a simple species made up of a fungus and a single-cell algae, were taken from the back seat.

Mr Eversham said although there was no monetary value to the lichens, the collection, some of which dated back to the 1970s and had been found in areas which no longer existed or identified by national experts who had since passed away, was “irreplaceable”.

Mr Eversham, chief executive of the Wildlife Trust for Bedfordshire, Cambridgeshire and Northamptonshire, said: “I was really distraught. Lichens were one of the first sorts of wildlife I became interested in and there were some from my first fieldwork back in the 1970s.

“It’s gradually dawned on me how much of my spare time was contained in those boxes. Although of no commercial value, the collection is of considerable interest and is irreplaceable.

“I probably visit Warren Lodge eight or nine times a year and it’s never happened before. I make a point of not leaving anything obviously valuable in the car but I didn’t think this looked like something that would be worth stealing.”

The lichens, which are sensitive indicators of air quality and pollution and useful in assessing the quality and conservation value of heathlands, were stored in envelopes which were in two plastic drawers, of the sort usually found in vegetable racks. Mr Eversham had taken them with him on a visit to the lodge to compare with those growing at the site and uses them on training courses run by the National Trust.

He now faces several long journeys to Scotland and Northern England to try to replace some of the collection but asked anyone who may find the lichens to come forward.

“If anybody’s got them they can let me know and I will assume they found them completely innocently and go and collect them,” he said.

“The police think they may have been disregarded somewhere but obviously the problem is that rain and envelopes don’t really mix.”

Norfolk Police confirmed they had been called following a theft of “wild flowers” which happened between 9.30am and midday on Brandon Road on December 10.

Anyone who may come across the stolen lichen should contact Mr Eversham on 07872 418277, or email brian.eversham@wildlifebcn.org