A pensioner was shocked to discover what she thought was a tomato plant growing in her garden was actually a deadly weed used by witch doctors to induce comas in America.

Tolworth resident Mary Yates discovered the plant when it began growing this season, and at first thought it was a tomato plant, then a Chinese lantern plant.

But then she saw a BBC programme about poisonous plants and discovered revealed it was actually a thorn apple, also known as devil’s trumpet, devil’s weed and stink weed.

It has spiky fruit, can grow up to 3ft tall and its poisonous flowers and seeds can cause hallucinations, hypothermia and painful photophobia that can last several days.

In America, the plant is known as jimson weed.

It got this name from Jamestown, Virginia, where British soldiers were drugged with it while attempting to suppress Bacon's Rebellion and spent 11 days appearing to have gone insane.

Ms Yates said: “I was really worried when I saw the programme about it. I have a grandson who comes to stay and I don’t want him touching it.

“The programme said they don’t exactly know what happens when you eat it because no one has lived to tell the tale.

“I just don’t know where it has come from. What if it is in the soil I bought, or the pot I put it in? I don’t know how worried I should be and I don’t know how to get rid of it safely.

“I don’t want to put to in the council bin in case I spread it.”

Jill Turner, a plant expert at Kew Gardens, thinks the plant is being spread because bird-feed manufacturers are adding its seeds to their mix and said the rising number of photographs sent in for identification suggested it was becoming widespread.

Advice to those worried about it in their garden was to remove it carefully using gloves and burn it thoroughly.

To stop it spreading, remove the seed heads before they dry out and burst.

This was also recommended because the seeds look like horse chestnuts and may attract children.