For years Juliet Nisbet has enjoyed the fruit from the orange tree in her conservatory.
So when she noticed yellow fruit hanging alongside the oranges she assumed they would turn the right colour as they ripened.
But the 48-year-old, who has gardened as a hobby most of her life, was stunned when the fruit remained yellow and ballooned into the size and shape of lemons. The 3ft high plant now has about 25 oranges and four lemons hanging from its branches.
Bitter harvest: Juliet Nisbet was baffled when lemons appeared on her prize orange tree
Mrs Nisbet, a staff nurse and mother-of-three from East Lothian, Scotland, bought the tree for £15 at a garden centre nine years ago.
It now takes pride of place in her conservatory as she has numerous visitors coming to see the curious fruit.
‘A lot of people have come round, including gardeners. They’re all baffled by it,’ she said.
‘When I first noticed I thought, “good grief”. I left it for a week and by then they were bright yellow and lemon-shaped.’
While she admits she has not yet tasted the lemons, she said: ‘They’re shaped like American footballs. They’re definitely lemons.
‘I don’t want to touch them because I don’t want to ruin it. Hopefully they should last for another month. I’ve been gardening all my life and I’ve never seen anything like this.’
However, Neil Fishlock, head of horticulture at Dobbies, where Mrs Nisbet bought the tree, believes he has solved the puzzle.
He said: ‘It’s a grafted tree and a shoot has popped out where the orange tree was encouraged to fuse with a lemon tree. Anything grafted can sprout spontaneously below the join on the stem but it’s unusual.
‘The lemons will potentially take over and kill off the oranges eventually.
‘It means she will enjoy lemon pie rather than marmalade – but for now, she has the choice of both.’