Friday, 10 November 2017

Giant Hogweed. (inspiration for the 1971 song by progressive rock band Genesis...Return of the Giant Hogweed)

Back in July 2017 it was widely reported that Giant Hogweed was spreading across the UK. Mike Duddy...Mersey Basin Rivers Trust... described it as "the most dangerous plant in Britain" and that it was a "massive issue" that needed tackling.

 Thankfully there have been no more reported sightings of this invasive plant since 2013 in the Central East Lakes region.

This post from three years ago has been updated to celebrate the continued absence of Giant Hogweed on or near National Trust land at Cockshott, Windermere, and Bridge House, Stock Ghyll, Ambleside after two years of eradication work!

Giant Hogweed is probably the most feared of all the invasive plants. Its sap is phototoxic; it contains furanocoumarins, a toxic glucoside that photosenisitises the skin causing phytophotodermatitis...a serious skin inflammation. Exposure to sunlight causes severe and painful blistering that sometimes requires hospitalisation.

Even many years after the initial contact, the victim's skin is likely to remain highly sensitised to sunlight. A small amount of sap in the eyes may possibly cause blindness.

Giant Hogweed is the only invasive plant I am aware of that has had a song written about it...and an apocalyptic one at that! Below are some exerpts.....

"Long ago in the Russian hills a Victorian explorer found the Regal Hogweed by a marsh; he captured it and brought it home..."

"Fashionable country gentlemen had some cultivated wild gardens in which they innocently planted the Giant Hogweed throughout the land..."

"Soon they escaped spreading their seed preparing for an onslaught threatening the Human Race..."

"Around every river and canal their power is growing..."

"Stamp them out, we must destroy them...!"

© GENESIS. Return of the Giant Hogweed. From the 1971 album 'Nursery Cryme.'

Giant Hogweed (Heracleum Mantegazzianum) is a spectacular and exotic plant that is native to the Caucasus region. It is in the umbelliferous family Apiaceae. Superficially it resembles Common Hogweed or Cow Parsley (Heracleum Sphondylium)....but on steroids!

Victorian explorers introduced the plants to the UK. Since then Giant Hogweed has become highly invasive in the UK and will shade out native plants because it grows so fast and so tall. 

Without adequate controls, Giant Hogweed will spread and become dominant very quickly especially along watercourses restricting access and in some cases blocking footpaths.

It often contributes to river bank erosion. When the plants die back in Winter only bare ground remains that in flood conditions may easily be washed away.

Giant Hogweed plants were found growing alongside the small watercourse by the National Trust/SLDC Cockshott and Ferrry Nab footpath, Windermere in June 2011. The one above measured about fifteen feet tall! (The large trenching spade is completely dwarfed!)

Even more appeared the following year and these also were dug up and burnt.

Giant Hogweed is classed as a biennial, or monocarpic perennial living up to seven years. In its final year it produces the massive, hugely impressive flower heads, seeding in late August.
Bridge House, National Trust, Ambleside.

More recently in June 2013, Giant Hogweed was discovered twenty yards downstream of Bridge House, Ambleside. These were dug up well before the flower heads could seed. So far there has been no recurrence of the plants here.

If you see Giant Hogweed please contact the landowner, if known, or the appropriate authority.
 Digging up Giant Hogweed alongside footpath linking Cockshott to Ferry Nab. Protective clothing, goggles, gloves and face mask essential!
One less Giant Hogweed at Ferry Nab. This specimen measured 10 feet but many grow much taller.

Image of Giant Hogweed only 3 yards from Trust land. This plant would have needed another growing season at least before it could develop the flower stem; one plant is capable of producing fifty thousand seeds. These may remain viable for up to fifteen years! 

"Turn and run...nothing can stop them!"...© Genesis 1971.
This is the top half of the flower stem of a Giant Hogweed dug up from the side of Stock Ghyll just a few yards from Bridge House. June 2013)

A message from  South Cumbria Rivers Trust...

South Cumbria Rivers trust are aiming to locate and eradicate invasive non-native species throughout the catchments of South Cumbria stretching from the River Duddon to the River Lune. Any sightings of the following species below would help us to focus our efforts over the coming seasons with priority within the Windermere, Coniston, and River Kent catchments:
Giant hogweed
Japanese knotweed
Himlayan balsam
American skunk cabbage
American signal crayfish
Killer shrimp

You can record a sighting via the CFINNS website: 
or email Jen on

1 comment :

  1. On the subject of invasive non native species, South Cumbria Rivers Trust have organised three Himalayan Balsam pulling events in the Windermere area for July. Please check their web site to find out more.