People urged to report sightings of 'harmful' giant hogweed

Giant hogweed, also known as Heracleum mantegazzianum, is considered dangerous as it can cause burns on people's skin and can leave you with blisters.

An interactive map has been published at whatshed.co.uk allowing people to report sightings of the harmful plant.

Here's all you need to know about the potentially dangerous giant hogweed.

What is giant hogweed? 

Giant hogweed, also known as Heracleum mantegazzianum, is a plant in the Apiaceae family.

The Apiaceae family includes other plants including parsley, carrot, parsnip, cumin and coriander.

Giant Hogweed originates from the Caucasus Mountains and Central Asia and was first introduced to the UK in the 19th century.

Is giant hogweed dangerous?

Giant hogweed is described but the Royal Horticultural Society (RHS) as "invasive and potentially harmful".

It can be dangerous as the sap from the plant can cause burns on one's skin.

The sap contains furocoumarin, which makes skin extremely sensitive to sunlight. 

The Woodland Trust said: "If the sap gets onto your skin and it's then exposed to the sun, your skin can blister badly.

"Blistering can then recur over months and even years."

The RHS added it can also cause pigmentation and long-lasting scars.

The trust adds the best way to avoid injury is to familiarise yourself with the plant and avoid contact with it.

Giant Hogweed can cause burning on your skin and leave you with blisters. (Image: Getty Images)

How to treat giant hogweed burns

If you do come into contact with giant hogweed, The First Aid Training Co-operative suggests you do the following:

• Immediately wash the area with soap and cool water
• Don’t burst any blisters. Seek medical help if they are extensive
• Stay out of any sunlight for at least 48 hours
• Thoroughly wash the clothes you were wearing when you came into contact with the plant
• Monitor for any delayed reactions

What does giant hogweed look like? 

Giant hogweed looks like an enormous cow parsley plant.

When it's fully grown, it can reach heights of between 1.5m to 5m and have a spread of between 1 and 2m.

According to the Woodland Trust there are four things to look out for which help identify Giant Hogweed:

Stems

The stems are green and often have purple blotches and stiff, white, brittle hairs.

They are hollow with ridges and have a thick circle of hairs at the base of each leaf stalk.

Leaves

The leaves can be quite large, up to 1.5m wide and 3m long, and are deeply divided into smaller leaflets.

It looks a bit like a rhubarb leaf, with irregular and very sharp or jagged edges.

The underside of the leaf is hairy.

Flowers

Flowers on giant hogweed appear in June and July.

They are small and white (or slightly pink) and are clustered on umbrella-like heads known as umbels that can reach a diameter of 60cm.

All the "umbrella-like heads" face upwards.

Seeds

Giant hogweed seeds are dry, flat, and oval-shaped.

They are almost 1cm long with tan with brown lines extending 3/4 of the seed length.