Ian Imrie said the tree grows about one foot per year.

Retired antiques dealer Ian Imrie has spent 21 years tending the tree at his home in Bridge of Earn.

Palm trees are known to grow in the west of Scotland thanks to the effects of the Gulf Stream, which transports warm tropical water to the area.

By contrast, the tree has proven notoriously difficult to grow in the colder east.

Ian, 68, who bought the tree two decades ago from an English plant dealer, said it had grown a foot in height each year since.

Everyone is baffled as to how I could grow one more than 20ft high in Bridge of Earn

Ian Imrie

As a Trachycarpuspus Fortunei or Windmill Palm, the tree has flowered at the start of every summer while growing to its enormous height.

Ian is convinced the phenomenon is thanks to heat from the exhaust of his gas-fired central heating system.

He said: "The experts say they can grow from six to 10ft tall at most, in some warmer parts of Britain, aided by the Gulf Stream.

"But everyone is baffled as to how I could grow one more than 20ft high in Bridge of Earn, on the east of Scotland.

"But to be honest, we think the exhaust from the house's heating system, which comes out nearby, has raised the temperature and helped it grow."

Ian, who also works as an artist, admitted even he had been surprised by the success of the tree, considering its location.

He added: "I just bought it because I like unusual plants. I've got a garden full of them, but the palm tree has done really well and it flowers every year."

'Absolutely amazing'

Palm trees can be a familiar site to visitors in some areas of the west coast of Scotland.

The fishing village of Plockton has a scenic harbour lined with palms due to the warmth brought by the Gulf Stream.

Ian's wife Margaret added: "It is absolutely amazing that it has grown to such a height in this part of the world.

"When Ian is not painting in his studio, he spends a lot of his time in the garden tending to his palm tree.

"It is our pride and joy."