Himalayan balsam: Call the Marines! It’s an alien plant invasion

Scientists, and now the military, are battling the spread of Himalayan balsam

An alien plant, so bothersome that Royal Marines have been called in to try to eradicate it, and so persistent that a top laboratory is working on a biological “secret weapon” to defeat it, has been helped to invade the British countryside by a fifth column of subversive flower lovers.

The Himalayan balsam grows up to 10ft (3m) tall and has colonised large areas beside rivers and woods throughout Britain, smothering any indigenous plants. The Environment Agency, Plantlife, Wildlife Trusts and the National Trust all say the species is a headache, and its total removal could cost as much as £300m.

But, with its pink orchid-like flowers, it is also attractive to many people. It’s so attractive, in fact, that a big factor in its invasive spread is people scattering its seed in the wild, according to research by Professor Ian Rotherham of Sheffield Hallam University and author of Invasive and Introduced Plants and Animals.

He has plotted its spread around the UK, and the novel reasons for it. Himalayan balsam (also known as Indian balsam) was introduced here in 1839 as a greenhouse and warm garden plant and, within a few decades, had escaped into the wild. It gradually established bridgeheads, and then, especially after the Second World War, spread rapidly. Professor Rotherham’s researches show that enthusiasts scattering its seeds far and wide were responsible.

Professor Rotherham’s work, presented to environmental managers some years ago but not to a wider audience, quotes some examples of people who assisted the invader. There was a Miss Welch who, in 1948, collected seeds from Sheffield and took them to the Isle of Wight, where she sprinkled them beside a river near Newport; a Mrs Norris of Camberley in Surrey, who spread them to local waste areas and woods, gave them to passers-by, sent seeds to Ireland and even took them on holiday to France and Spain; plus people who, in recent decades, have carried the species from Norfolk to Newcastle, Aberdeenshire to Leicestershire, Hertfordshire to Essex and Bedfordshire, and Sheffield to the Peak District. Thus, the plant, also known because of the shape of its flowers as “policeman’s helmet”, spread. As Professor Rotherham puts it succinctly: “People like it!”

And once growing, Himalayan balsam can proliferate at a fearsome rate. Each plant produces an average of about 800 seeds, which means that a dense mass of the plants can contain a potential 30,000 seeds per square metre. And the explosive fruit pods can project the seeds several metres. So entertaining can it be to see the pods “pop” that it has even been marketed as a novelty for children – “Mr Noisy’s Exploding Plant” – once sold by, among other outlets, Birmingham Botanical Gardens.

The upshot is that there is barely a part of lowland Britain free of this pretty menace. Fat stands of it clog small streams in places such as Somerset, and mass on the banks of rivers and woods from Cornwall to Scotland, with Norfolk, the Isle of Wight, New Forest, Hampshire, County Durham, Yorkshire, west Cumbria, Lancashire and North and South Wales especially troubled by it. The species is so prolific near Liverpool that it is known there as “Mersey weed”. Himalayan balsam grows in almost impenetrable thickets and will bully out any other species; its plentiful nectar means that bumble bees pollinate it rather than native species, and, being an annual, it dies down, leaving riverbanks bare in winter.

That is why, every summer weekend, conservationists organise clearing parties. This month, Royal Marines from the Commando Training Centre at Lympstone, Devon, joined volunteers to uproot the plants growing beside tributaries of the River Otter. Wildlife Trusts as far apart as North Wales, Surrey and Cambridgeshire are calling up volunteers for anti-balsam efforts, and Professor Rotherham is working with groups on the urban River Don.

But, as fast as it is cleared, it pops up elsewhere. A native of India and Pakistan, it has invaded 23 European countries, New Zealand, the US and Canada. The ecological and financial cost of this is one reason why the laboratories at the Centre for Agricultural Bioscience International (Cabi) in Surrey have been working on a biological solution.

Cabi scientists have discovered a rust fungus which seems to attack only Himalayan balsam and no other plant. If their safety tests find no problems, permission for the controlled release of the rust species will be requested from UK regulators. And, if all else fails, we could always eat it. All parts of the plant are edible, and the seed pods, according to Richard Mabey’s authoritative Flora Britannica, have “a pleasant nutty taste”.

Start your day with The Independent, sign up for daily news emails
ebooks
ebooksAn introduction to the ground rules of British democracy
Latest stories from i100
Have you tried new the Independent Digital Edition apps?
SPONSORED FEATURES
Independent Dating
and  

By clicking 'Search' you
are agreeing to our
Terms of Use.

iJobs Job Widget
iJobs General

Recruitment Genius: Field Sales Consultant - Financial Services - OTE £65,000

£15000 - £65000 per annum: Recruitment Genius: This is an exciting opportunity...

Recruitment Genius: Loan Underwriter

£18000 - £20000 per annum: Recruitment Genius: This is a fantastic opportunity...

Recruitment Genius: Collections Agent

£18000 - £20000 per annum: Recruitment Genius: This is a fantastic opportunity...

Recruitment Genius: Sales Negotiator - OTE £23,000

£13500 - £23000 per annum: Recruitment Genius: This award winning, Bolton base...

Day In a Page

The Silk Roads that trace civilisation: Long before the West rose to power, Asian pathways were connecting peoples and places

The Silk Roads that trace civilisation

Long before the West rose to power, Asian pathways were connecting peoples and places
House of Lords: Outcry as donors, fixers and MPs caught up in expenses scandal are ennobled

The honours that shame Britain

Outcry as donors, fixers and MPs caught up in expenses scandal are ennobled
When it comes to street harassment, we need to talk about race

'When it comes to street harassment, we need to talk about race'

Why are black men living the stereotypes and why are we letting them get away with it?
International Tap Festival: Forget Fred Astaire and Ginger Rogers - this dancing is improvised, spontaneous and rhythmic

International Tap Festival comes to the UK

Forget Fred Astaire and Ginger Rogers - this dancing is improvised, spontaneous and rhythmic
War with Isis: Is Turkey's buffer zone in Syria a matter of self-defence – or just anti-Kurd?

Turkey's buffer zone in Syria: self-defence – or just anti-Kurd?

Ankara accused of exacerbating racial division by allowing Turkmen minority to cross the border
Doris Lessing: Acclaimed novelist was kept under MI5 observation for 18 years, newly released papers show

'A subversive brothel keeper and Communist'

Acclaimed novelist Doris Lessing was kept under MI5 observation for 18 years, newly released papers show
Big Blue Live: BBC's Springwatch offshoot swaps back gardens for California's Monterey Bay

BBC heads to the Californian coast

The Big Blue Live crew is preparing for the first of three episodes on Sunday night, filming from boats, planes and an aquarium studio
Austin Bidwell: The Victorian fraudster who shook the Bank of England with the most daring forgery the world had known

Victorian fraudster who shook the Bank of England

Conman Austin Bidwell. was a heartless cad who carried out the most daring forgery the world had known
Car hacking scandal: Security designed to stop thieves hot-wiring almost every modern motor has been cracked

Car hacking scandal

Security designed to stop thieves hot-wiring almost every modern motor has been cracked
10 best placemats

Take your seat: 10 best placemats

Protect your table and dine in style with a bold new accessory
Ashes 2015: Alastair Cook not the only one to be caught in The Oval mindwarp

Cook not the only one to be caught in The Oval mindwarp

Aussie skipper Michael Clarke was lured into believing that what we witnessed at Edgbaston and Trent Bridge would continue in London, says Kevin Garside
Can Rafael Benitez get the best out of Gareth Bale at Real Madrid?

Can Benitez get the best out of Bale?

Back at the club he watched as a boy, the pressure is on Benitez to find a winning blend from Real's multiple talents. As La Liga begins, Pete Jenson asks if it will be enough to stop Barcelona
Athletics World Championships 2015: Beijing witnesses new stage in the Jessica Ennis-Hill and Katarina Johnson-Thompson heptathlon rivalry

Beijing witnesses new stage in the Jess and Kat rivalry

The last time the two British heptathletes competed, Ennis-Hill was on the way to Olympic gold and Johnson-Thompson was just a promising teenager. But a lot has happened in the following three years
Jeremy Corbyn: Joining a shrewd operator desperate for power as he visits the North East

Jeremy Corbyn interview: A shrewd operator desperate for power

His radical anti-austerity agenda has caught the imagination of the left and politically disaffected and set a staid Labour leadership election alight
Isis executes Palmyra antiquities chief: Defender of ancient city's past was killed for protecting its future

Isis executes Palmyra antiquities chief

Robert Fisk on the defender of the ancient city's past who was killed for protecting its future