A conservation worker was forced to take action himself after authorities did nothing to tackle an “extremely dangerous” invasive plant.

Sandy Belloni, who runs a local action group Community Connections Project that deals with invasive species, spotted Giant Hogweed plants on the verges of the M1 motorway near Elstree and alongside footpaths.

The plant can cause “terrible” burns to humans and animals if it touches the skin, and after getting to emails warning of the problem, he removed seed heads himself to stop the plant spreading.

Mr Belloni said: “I’ve been dealing with invasive species for many years and was disappointed with Highways England’s lack of response when I approached them.

This Is Local London: Map showing spots where Giant Hogweed is rifeMap showing spots where Giant Hogweed is rife

“If we don’t take urgent action to control this plant, it will rapidly spread, affecting numerous other landowners and users and become much, much harder and more expensive to manage.

"If people are unaware of this plant, simply rubbing past it can cause permanent scarring."

The conservation worker first spotted the plants growing beside the motorway and footpaths in late June.

After he reported this to Highways England, Herts Highways and Herts County Council, Highways England responded saying it would be cutting giant hogweed to stop seed spread, and treat it next year.

This Is Local London: Sandy BelloniSandy Belloni

And on July 19, he called again, having noted that no action had been taken yet, and seeds were already dropping from the plants.

On July 27, he received an email from Highways England. This said it had identified one specimen of Giant Hogweed within its boundary and would be carrying out work within the next two to three weeks.

Mr Belloni said: “In early August, having seen no action and seeds falling from plants, I attended the sites shown on the map and cut, removed and destroyed 39 seed heads containing an estimated 300,000 seeds.

“There are still thousands of young plants in these areas. I’ve been speaking to the Environment Agency who intend to remind landowners not to neglect their responsibilities in relation to giant hogweed.”

This Is Local London: Sandy BelloniSandy Belloni

Mr Belloni said that Giant Hogweed is often over 7” tall, has stems the girth of one’s wrist and flower heads the size of a large dinner plate.

He and his team use both chemical and manual methods to control Giant Hogweed.

He added: “I very much want to speak to relevant landowners to show them the specific areas concerned and discuss the actions required to co-ordinate control of this extremely dangerous invasive species.”

Highways England's regional highways manager Ian Clabon said: "We are aware of the issues around the stretch of M1 at Munden, and our contractors are currently dealing with the issues there.

“We manage vegetation along the M1 in a number of different ways throughout the year and treat fast growing weeds like Hogweed that would otherwise risk obscuring signs and blocking drainage.

“Our contractors use specialist protective equipment when spraying weeds along the verges of our network.

“It is dangerous for a member of public to undertake this work themselves. Safety is our number one priority and we would ask members of the public to leave this work to our professional team.

“We are in contact with the customer and keep them updated on the plan.”

If people spot the plant, they can report it to Sand Belloni at Community Connection Projects CIC here: http://ccprojects.co.uk/