Located within Benmore Botanic Garden, near Dunoon, the imposing stone and glass structure is the result of a £550,000 project led by the Royal Botanic Garden Edinburgh (RBGE).

It is hoped that the fernery will become a major tourist attraction for Argyll. One hundred guests will attend the official opening ceremony performed by Culture Minister Michael Russell and Sir Peter Hutchison, chairman of the Younger (Benmore) Trustees.

Alan Bennell, RBGE’s head of visitor services said: “We’ve been to the other ferneries in Britain -- some of them are terrific, but there is absolutely nothing quite like this.

“Benmore, is a lovely garden but it’s hard trying to get people to cross the Clyde, no matter how hard we try,” said Mr Bennell. “This should make people sit up and say, ‘Look at this remarkable feature,’ and give them that extra spark to come and visit. I’d be disappointed if our visitor numbers don’t show that.”

Benmore Botanic Gardens stretches to 120 acres, boasts 12,000 plants and is best known for its 300 rhododendrons. Situated seven miles north of Dunoon, it attracts 30,000 visitors a year.

Peter Baxter, curator at Benmore, said: “The fact that we’ve got a wonderful rock gully as you approach the fernery, the combination of the planting of that and this unique building means that we have something very special at Benmore.”

The humble fern is often overlooked today but in Victorian times it was the focus of a nationwide obsession. The fernery at Benmore is a legacy of this pteridomania or “fern craze”.

Professor Mary Gibby, director of science for RBGE, is one of the UK’s foremost experts on ferns. “Such a magnificent building would have caused huge excitement in its heyday,” she said.

The fernery was first built in the early 1870s, when much of the garden was planted, for the wealthy Glasgow sugar merchant James Duncan. It was abandoned at the start of the First World War and gradually fell into disrepair.