It looks like a watermelon but is the size of a grape and tastes something like a cross between a cucumber and a lime.

The tiny cucamelon is not some genetically modified laboratory creation, but rather an import which originated in the wilds of Mexico thousands of years ago.

And now, it has reached the high street as a grow-your-own plant alongside tomatoes, cucumbers and lettuce.

Cucamelon plants and Indigo Rose tomato plants go on sale in 50 Waitrose branches costing £4 a pot

Waitrose is to offer pots of the vines that produce the cucamelons as part of a wider collection of plants that can be grown on a windowsill, tub or a vegetable plot.

The cucamelon plants have been grown by Suttons Seeds in Yorkshire and are part of a range created by James Wong, the Kew-trained botanist, science writer and author of the book Homegrown Revolution.

It also includes several salad tomato varieties, sweetcorn, cucumber and peppers, including the powerful Scotch Bonnet chilli.

Mr Wong said: ‘The cucamelons can be eaten straight off the plant, or tossed with olives, slivers of pepper and a dousing of olive oil for a quirky snack with drinks - or even popped in a martini.’

The versatile plants can be grown easily and in the same way as a regular cucumber.

And there is no need for the cover of a greenhouse as long as there isn’t a risk of frost.

The cucamelon, which has the Latin name Melothria scabra, is a vine grown for its edible fruit which originated in Mexico and Central America.

Other common names include sandiita or little watermelon, mouse melon, Mexican sour gherkin, Mexican miniature watermelon and Mexican sour cucumber.

They are pest and drought resistant and, in theory, the slow-growing vines can eventually grow up to ten feet under proper conditions.

Range-creator James Wong said: ‘The cucamelons can be eaten straight off the plant, or tossed with olives, slivers of pepper and a dousing of olive oil for a quirky snack - or even popped in a martini.’

Victoria Mason, Waitrose outdoor plant buyer, said: ‘We know that, after cooking, gardening is our customers’ favourite hobby, so we wanted to introduce something a little bit out of the ordinary that they can grow and enjoy.

‘This fun fruit is easy to grow so is the perfect plant for all ages to try their hand at gardening.

'The new James Wong range shows you don’t have to stick with the traditional when growing your own vegetables and offers some exciting new additions for our customers’ gardens.’

The plants will be available from wednesday and will be in the majority of Waitrose branches by the end of April.