The horrific plant, which is native to the Caucasus, can cause debilitating burns and blisters that last up to seven years – just by touching the stem or leaves. Authorities have been warning people to stay away from the plant, which tends to grow in wild areas alongside footpaths and watercourses. Head Gardener at Alnwick Castle, Trevor Jones, warned Express.co.uk that the problem is only going to get worse.
He said: “If you allow it to flower, the flowers will produce seeds.
“So from one flowerhead you might get 1500 seeds and they will blow about in the wind.
“They will fall into water courses especially.
“And they’ll be transported by the watercourse onto other riverbanks.
“They germinate very, very easily and within two years you have this enormous plant that will be up to eight foot.
“And then it does it all again.
“So yes, it’s spreading and it has become a major problem throughout watercourses in the UK.
Mr Jones shared a gruesome anecdote about a colleague who had fallen foul of the virulent eight-foot plant.
He explained: “It’s phototoxic which means if you brush against it and you get the sap onto your skin then you start to form blisters.
“We actually had a gardener that was working in our poison garden without protective gear on and she actually did exactly that – brushed against the plant.
“And the back of her hands started to swell and within three hours she was taken to the hospital.
“She ended up with third-degree burns from this plant.
“Now, one of the issues with this is once the toxin is in your system it stays there for up to seven years.
“So every time she goes out in sunlight the blisters start to re-form.
“So there are some pretty dangerous plants like that that people should be aware of.”
The pest was introduced to the UK in the 19th century as an ornamental plant.
The severe reaction to the plant is caused by the presence of linear derivates of furanocoumarin in the plant’s leave, seeds, flowers, roots and stems.
These chemicals enter the nucleus of human epithelial cells, form bonds with the DNA and cause cells to die.
Commenting on the danger of the plant, Mike Duddy, River Trust expert, said: “If you don’t know what the plant is, it’s exceedingly dangerous.
“It is, without a shadow of a doubt, the most dangerous plant in Britain.”
The Wildlife and Countryside Act 1981 made it illegal to plant or cause giant hogweed to grow in the wild.
Due to the plant’s phytotoxicity and invasive nature, giant hogweed is often regularly removed.
Giant Hogweed has a stout, bright green stem with dark red spots and hollow red-spotted leaf stalks.
Stems typically grow more than two metres high.
The plant also produces white flowers which are clustered in an umbrella-shaped head.