Poison arrow plant found in British garden

Daffodils, heart's ease and phlox might be expected in an English country garden – and hollyhocks and forget-me-nots – but a hallucinogenic and highly toxic South American plant used for poison arrowheads might seem a little out of place.

But that was exactly what Sharon Nowell found when she went wandering among the shrubs and blooms of her parents' garden in Keresley near Coventry. At first she spotted what she assumed to be a weed, but as it looked interesting she decided not to dig it up to see how it developed.

A month later it had grown four feet and convinced Ms Nowell and her parents, Anne and Norman, that it was far from native to the Midlands. By searching through pictures on the internet she identified it as Datura stramonium, more colloquially known as the devil's trumpet, the devil's apple, the devil's snare, thorn apple and jimson weed.

Almost as soon as she had identified it, she was inundated with online messages from far and wide warning her that it was highly toxic. The species originates from South America, where it has been used by tribespeople as a toxin on arrowheads to incapacitate prey. It has also been sold in the US as jimson weed, which is used to produce a hallucinogenic effect.

"I was gobsmacked when I found out about it being hallucinogenic," said Ms Nowell. "It's a really dodgy plant to have in a garden. We thought it was a marrow or something. My parents know exactly what is in their garden so they knew they hadn't planted it. Out of curiosity we decided to let it grow and it's flourished. It's been growing about a foot a week. It's a monster now."

Professor Monique Simmonds of the Royal Botanic Gardens at Kew said the plant has become established in parts of Europe, including France, and it is possible that it will be able to survive a British winter. It is also likely that it has appeared in Britain before, as its toxins have been identified contaminating garden refuse and other products.

"It's been associated with problems with horses and possibly humans before. The flowers are very visual but I wouldn't have thought they would be something people would grow widely. The problem is they get into other materials," Professor Simmonds said.

The plant in Keresley is thought to have hitched a lift from a consignment of other plants being imported into Britain. Alternatively, its seeds might have been included accidentally in bird food brought into this country and sold in pet shops or garden centres, before landing in the Nowell family's garden in the form of a bird dropping.

Professor Simmonds said: "It's hallucinogenic but it's not a plant shamans would have used. It's quite a mild hallucinogenic, and is not in the same class as LSD. The problem is that after the hallucinogenic effects come the toxins. People have used it mixed with flour to get a high. It's one of those things people have taken for a near-death experience."

A spokesman for the Royal Horticultural Society added: "These plants are not native to Britain and we think it arrives in bird seed sold to feed wild birds and generally grown in hot countries where Datura is a very common weed.

"They belong to the same family as deadly nightshade and are highly poisonous if eaten, but they should pose no threat if treated carefully, and unwanted plants can be consigned to the compost bin or green waste collection."

Ms Nowell's mother, Anne, said: "On the internet it says it is poisonous, so Sharon has been telling everyone that her dad is growing drugs in the garden."