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Giant hogweed – and why to avoid it!

giant hogweed

I was recently exploring the edges of a field near where I live when I came across a jungle of giant hogweed plants. As their sap can cause extremely nasty and painful blisters, I avoided getting too close to them. I also thought it would be good to warn readers to steer clear of giant hogweed too!

The giant hogweed of Kortenberg
The giant hogweed jungle of Kortenberg!

But first, here’s a quiz question to ponder while you read the post. The answer will be revealed later.

What is the connection between giant hogweed and the famous English drummer, singer-songwriter, record producer, and actor Phil Collins?

What is giant hogweed?

Giant hogweed (Heracleum mantegazzianum) is a plant in the Apiaceae family (previously known as the Umbelliferae). Don’t be put off by the Latin; this family includes well-known wild flowers such as cow parsley and wild carrot.

Cow parsley flower
The related, more familiar, and perfectly safe, cow parsley

Where does the giant hogweed come from?

The giant hogweed isn’t native to Europe. Its home is central Asia and the Caucasus Mountains. But in the early 19th century it was brought to the UK and planted as an ornamental garden flower. It soon escaped, and found the UK’s soils and climate to its liking. It then hopped over the Channel and is now naturalized through much of Europe, including Belgium. It was also introduced to parts of the USA and Canada.

What does it look like?

It looks like a very large cow parsley. It has the same familiar white umbrella-shaped flower heads. However, when you see a giant hogweed you’ll know it’s a giant hogweed because … it’s huge! Cow parsley grows to about one meter high, perhaps 1.5 meters at the most. Giant hogweed can reach 3, 4 or even 5 meters in height! Whereas the flower heads of cow parsley can be 15-25 cm wide, those of giant hogweed can be 60 cm.

Giant hogweed flowers
The flowering head of giant hogweed

The leaves are different too. Cow parsley leaves are tripinnate, which means that the leaves are divided, and then those divisions are also divided. This gives quite a feathery appearance. The leaves of giant hogweed are huge – they can be 2 or 3 meters long. They are irregularly shaped, and have very sharp or jagged edges. The underside of the leaves is hairy.

Giant hogweed leaves
Giant hogweed leaves

The stems of the giant hogweed are usually green, with purple blotches and stiff, white, bristly hairs.

Note the jagged leaves and purplish stems of giant hogweed

Basically, if you are walking along and need to look upwards at something that looks like cow parsley – it’s giant hogweed.

Why you need to avoid touching giant hogweed

The sap of the giant hogweed contains a substance called furocoumarin. This makes skin extremely sensitive to sunlight, a phenomenon called phytophotodermatitis. If the sap gets onto your skin, and then the skin is exposed to sunlight, you will feel a painful burning sensation. The skin may blister badly. I’m not going to include any photos here, but if you click this link you’ll get the message. (Not for the squeamish).

What should you do if you touch giant hogweed?

If you think you have got giant hogweed sap on your skin – for example when you are out walking – three things need to be done. Thoroughly wash the area with water as soon as you can. At the same time, try to protect the area from the sun’s rays. You are then advised to seek medical advice.

The best thing to do to avoid injury is to familiarize yourself with the plant and don’t go anywhere near it.

What’s the link between giant hogweed and Phil Collins?

Have you worked out the answer? You probably have to be of a certain generation, and with a certain interest in rock music. Phil Collins was drummer of the great rock band Genesis. One of the tracks on their 1971 Nursery Cryme album is entitled “The Return of the Giant Hogweed.”

The lyrics cleverly tell the story of the discovery of the plant in Russia and its “capture” by a botanist who brought it to Kew Gardens. It describes the plant’s toxicity, although then humorously suggests the plant is planning to take over the human race. This suggests a nod to the 1951 novel “The Day of the Triffids.”

Here’s the track, and the lyrics are underneath:

“The Return of the Giant Hogweed” – Genesis

Turn and run!
Nothing can stop them
Around every river and canal their power is growing
Stamp them out!
We must destroy them
They infiltrate each city with their thick dark warning odour
They are invincible
They seem immune to all our herbicidal battering

Long ago in the Russian hills
A Victorian explorer found
The regal Hogweed by a marsh
He captured it and brought it home

Botanical creature stirs! Seeking revenge…
Royal beast did not forget
He came home to London
And made a present of the Hogweed
To the Royal Gardens at Kew

Waste no time!
They are approaching
Hurry now, we must protect ourselves and find some shelter
Strike by night!
They are defenceless
They all need the sun to photosensitize their venom
Still they’re invincible
Still they’re immune to all our herbicidal battering

Fashionable country gentlemen
Had some cultivated wild gardens
In which they innocently planted
The Giant Hogweed throughout the land

Botanical creature stirs! Seeking revenge…
Royal beast did not forget
Soon they escaped, spreading their seed
Preparing for an onslaught
Threatening the human race

Mighty Hogweed is avenged!
Human bodies soon will know our anger
Kill them with your Hogweed hairs!
Heracleum Mantegazziani

  • Songwriters: Peter Gabriel / Anthony Banks / Phil Collins / Steve Hackett / Mike Rutherford
  • The Return of the Giant Hogweed lyrics © Stratsong Ltd., Stratsong Limited

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14 thoughts on “Giant hogweed – and why to avoid it!”

  1. My arm was badly burned in 2004 after pruning a Giant Hogweed, sold to me that Spring by a plant nursery. Neither Dr nor pharmacist could identify cause of symptoms – plant relatively unknown at the time. The dermatologist did, however, and advised me to destroy plant. Which i did. I still have scars.

    1. Ouch that sounds a painful experience Alison, thanks for sharing it here. I don’t think nurseries still sell it nowadays as it’s on lists of toxic and dangerous plants. Indeed in some countries it’s illegal to sell it.

  2. Some great pictures of it. A stunning plant despite it’s dangers.
    Himalayan Balsam – now there is an alien pest!

  3. No giant hogweed in or near my garden, but a plant of poison hemlock (Conium maculatum) turned up once. It belongs to the same family as hogweed and is most definitely not to be eaten! I removed it promptly.

  4. Wow, what a stunning plant! I can well understand why the Englishman thought it would be great as a gardener’s delight. I will be sure to keep my distance: Those blisters are unsightly and probably very painful.

  5. This is important information for anyone who likes rambling around the countryside and admiring plants. After spending 4-weeks healing from an evil rash I picked up while tangling with poison oak vines (a cousin to poison ivy), I fully agree that educating oneself and avoiding some plants is the smart way to go.

    1. Ouch! That doesn’t sound good Henry, although as you say, it’s a practical demonstration of the importance of knowing what you are tangling with. I hope you are now back to full health again.

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