A TOXIC plant that can cause massive blisters and ulcers if touched has been reported in various areas across London.

Giant Hogweed can also cause blindness if it comes into contact with the eyes.

An interactive map has been published, allowing people to report sightings of the toxic plant.

Known as Britain's most dangerous plant, it has been spotted this year so far, in Wimbledon, Hackney, Ealing, Kingston upon Thames, Stratford, East Ham, Tottenham, and a few others which you can see via the website. 

This is everything you need to know about Giant Hogweed, from what it looks like to why it’s dangerous - and what to do if you touch the toxic sap.

East London and West Essex Guardian Series:

What is Giant Hogweed and is it dangerous?

Giant Hogweed, also known by its Latin name Heracleum Mantegazzianum, originated in Southern Russia and Georgia.

The plant is part of the Apiaceae family, which includes well known vegetables and herbs like parsley, carrot, parsnip and coriander.

Giant Hogweed was introduced to Britain and Europe in the 19th century, from the Caucasus Mountains.

The earliest documented reference to the plant has been traced back to the Royal Botanic Gardens Kew Seed List of 1817, where seeds of the plant were listed.

The plant itself can reach over 10ft in height and, according to The Royal Horticultural Society (RHS): “most gardeners will want to eradicate it, as it is potentially invasive and the sap can cause severe skin burns”.

The sap contains a chemical called furocoumarin which makes the skin sensitive to the sun, which can cause bad blistering. The blistering can even recur over the span of months, and even years.

What does Giant Hogweed look like?

The Woodland Trust outlines the appearance of Giant Hogweed so that you can better identify the dangerous plant.

  • Stems: the stems are green with purple blotches and stiff, white hairs. The stems are hollow with ridges and a thick circle of hair at the base of each leaf stalk
  • Leaves: the leaves are huge, and can measure up to 1.5m wide and 3m long, and are often divided into smaller leaflets. The Woodland Trust compares them to rhubarb leaves, with irregular and jagged edges, with the underside of the leaf being described as hairy
  • Flowers: the flowers of the Giant Hogweed appear in June and July, and are small and white and appear in clusters on “umbrella-like heads” that face upwards.

Where am I likely to find Giant Hogweed?

The plant is found throughout the UK, and more specifically, by river banks where the seeds are transported via the water.

The RHS also says that areas affected by Giant Hogweed include “gardens and allotments adjacent to infected woodland, healthland or common land”.

You can view the distribution of Giant Hogweed reports across the UK on the Plant Tracker website.

You can zoom into specific regions of the UK to see how many reports of Giant Hogweed have been made in certain areas.

How do I treat Giant Hogweed burns?

If you accidentally get Giant Hogweed sap on your skin, Healthline says that you should wash the area with mild soap and cool water as quickly as possible. You should keep the skin covered when you’re outside to protect it from the sunlight.

If a rash or blister begins to form, you should seek medical attention. Your treatment will depend on how severe your reaction is.

“Skin irritation that’s caught early might be treated with a steroid cream and nonsteroidal anti-inflammatory drugs, such as ibuprofen, to relieve pain,” Healthline explains.

“Severe burns could require surgery to graft new skin over the damaged skin.”

Healthline also explains that the Giant Hogweed sap can damage more than just your skin - if the sap gets in your eyes, you can experience either temporary or permanent blindness. Similarly, breathing in sap particles can result in respiratory problems.

Seeds: the seeds are dry, flattened and an oval shape, almost 1cm long and tan in colour with brown lines