A deadly tropical plant used for its poison by South American tribes has been discovered by a retired couple in their Bristol garden.

Datura stramomium, also known as Devil's snare, is highly poisonous and used by South American Indians for lacing their hunting spears and fishing hooks.

It is also hallucinogenic and used by Hindu monks in sacred ceremonies. The seeds of the plant are particularly poisonous if eaten.

The poison causes dry mouth, blurred vision, heart irregularities, hallucinations and can cause coma and death in severe cases.

The plant shot to fame after featuring in JK Rowling's first boy wizard book – Harry Potter and the Philosopher's Stone where it was used as an obstacle for would-be thieves.

However, Graham, 70, and Wendy Till, 68, knew nothing of its dangers until their Whitchurch neighbour came racing round with a national newspaper article.

Retired electrician Mr Till said: "We got back from France and this strange plant was in the garden. It's around three feet now and if we left it, it would probably grow to six feet.

"I thought it was quite an attractive plant and I was going to leave it in but we were baffled to what it was.

"We took some photos of it and went to a garden centre but they didn't know what it was and said it was probably just a weed with some thistles growing from it.

"We came back from there and our next door neighbour came round with a copy of The Sun newspaper saying it was the same as in a story she had read. I have to admit we were a bit shocked by what we read and from then on we kept our distance.

"One of our other neighbours was even going to have a cutting off it ,but he has changed his mind now as you can imagine."

Mrs Till said: "I had pulled some of the dead flowers and leaves off it and I was a bit poorly afterwards and had a tight chest.

"I can't say for sure whether it was the plant but it does seem a bit of a strange coincidence.

"It's a mystery where it came from but we have to assume it either was bird droppings on perhaps from a bag of seeds we hung up for the birds. Now we know that we have to wear gloves.

"We have not told our grandchildren or great-grandchildren about the Harry Potter link yet because some of them are very young and we would not want them to get ill."

Mr Till added: "We will ring the Royal Horticultural Society and check which is the best way to dispose of it but at the moment I am thinking of cutting it up into little pieces and bagging it up for disposal.

"As far as we are concerned it is pretty dangerous and something a child could be attracted to so we need to get rid of it as soon as possible. It's also possible that someone with small children may see this and realise they have one in their garden and they need to get rid of it as soon as they can."

Nicole Russell, a spokeswoman for the Royal Horticultural Society, said: "Plants that have set seed should be binned or burnt in order that the seed does not disperse in the garden or persist in the compost heap. Always wear gloves or thoroughly wash hands after handling this plant."