HE always knew there was something weird about the slightly sinister- looking plant growing in his back garden.

But Chris Chattaway was shocked to discover the unwanted addition to the greenery behind his home is capable of causing hallucinations, amnesia and even comas.

The weed, which is covered in spiky seed pods, appeared beside his pond about two months ago and started expanding at a phenomenal rate.

Despite a lifetime working at nurseries across the New Forest, Mr Chattaway was unable to identify it – and neither could anyone else.

He eventually rang Kew Gardens and was referred to the Natural History Museum, which finally solved the riddle.

Datura Stramonium is also known as Thorn Apple, but has also been given more sinister names such as Devil’s Weed, Devil’s Trumpet and Hell’s Bells.

However, most cases of poisoning result from drinking a tea made from the seeds, either for its medicinal benefits or hallucinogenic effects.

Thorn Apple prefers a warmer climate than the UK and is relatively rare in Britain, although experts say it is becoming more common.

Mr Chattaway, 58, of Brockenhurst, said the plant probably grew from a seed dropped by a bird.

He added: “Despite working in nurseries for more than 30 years I’d never seen anything like it. I just knew it was something weird.

“The person I spoke to at the Natural History Museum knew straight away what it was, and when I did some research I came across some rather disturbing words such as ‘poisonous’, ‘coma’ and ‘hallucinogenic’.

“You’re supposed to wash your hands after touching it. I pricked my finger on it the other day but haven’t suffered any ill effects.

“I want to see how big it grows. After that I’ll probably burn it.”

A Royal Horticultural Society spokesman added: “The potentially harmful poisonous and hallucinogenic properties of this plant can sound alarming but a few simple precautions will enable gardeners to handle it without great risk.

“Always wear gloves or thoroughly wash your hands after touching the plant.”