The next Japanese knotweed? Expert sounds alarm over FOUR invasive weeds taking root across the UK – including the highly poisonous Devil’s Trumpet

Capable of taking over homes and regrowing from a one-centimetre fragment, an invasion of Japanese knotweed is any gardener’s worst nightmare^[1].

But experts now warn that the clumping Japanese weed^[2] is not the only intrusive plant gardeners need to be worried about.

Weed removal specialists from Environment Controls^[3] say there are four invasive plants taking root all over the UK.

That includes a wave of highly toxic Datura stramonium, otherwise known as the Devil’s Trumpet. 

Devil’s Trumpet is so toxic to both humans and animals that even touching it can be dangerous.

Experts warn that this invasive species should never be handled without the proper protective equipment. 

Jennifer Holmes from Environment Controls says: ‘Most people think of plants such as Hemlock as being a threat to human health, as it’s highly toxic if ingested.

‘But there are many other plants that can cause allergic reactions or are harmful both to man and the environment.’

Japanese knotweed might be most gardeners’ worst nightmare, but experts now warn that there are four other invasive plants you need to watch out for (stock image) 

Devil’s Trumpet

Part of the Datura family, this invasive plant is sometimes called thorn apple, devil’s snare, or jimson weed.

When fully grown, the plant is easily identified by ragged, pointy leaves and spiky seed capsules.

While some gardeners prize the exotic plant as an ornamental annual, it produces large quantities of seeds and can spread rapidly. 

Those seeds can remain dormant in the soil for years and grow fast enough to out-compete native plants for moisture, space, and nutrients. 

The Royal Horticultural Society says that you don’t necessarily need to remove devil’s trumpet from your garden, but warns that it is highly poisonous.

All parts of the plant are poisonous, and it must never be handled without protective equipment since it can cause skin irritation on contact. 

Consuming the plant can lead to severe health issues, including confusion accompanied by vivid auditory and visual hallucinations. ^[4]

The Devil’s trumpet (pictured) is an invasive and highly toxic plant now spreading across the UK. Experts warn that it should never be handled without protective equipment 

Shallon (Gaultheria shallon) 

Although non-toxic, Shallon or Salal is a highly aggressive invasive plant that can wreak havoc on local ecosystems.

This plant is an evergreen shrub which creates dense thickets up to 1.5 metres high that smother native life.

It is identifiable by its shiny, leathery leaves and small, pink and white urn-shaped flowers.  

Shallon was initially introduced into the UK to provide cover for game birds, but has since become highly invasive.  

Environment Controls recently discovered a significant infestation of this invasive evergreen shrub during a customer survey.

Shallon is a particularly big concern for UK ecology since it rapidly covers large areas of ground and prevents tree growth.

Dense thickets are very difficult to remove and can have profound impacts on areas of ecological importance.

Shallon (pictured) is an extremely aggressive shrub which spreads quickly and forms dense thickets. Conservation experts are concerned because this plant prevents forest regrowth in ecologically important areas  

This plant is so invasive that it is now an offence for residents in Scotland to plant or allow this species to grow wild. 

Tree of Heaven (Ailanthus altissima) 

Originally native to China, the Tree of Heaven is rapidly becoming one of the most concerning invasive plants in the UK.

The tree is extremely resistant to pollution, grows well in urban areas, and is becoming more widespread as the climate warms.

The tree spreads via windborne seeds and can quickly grow to heights of up to 80 feet.

In warmer European climates it is known to damage building foundations, sewers, and drains with its roots. 

The Tree of Heaven is also mildly toxic, and its sap can trigger dermatitis upon contact. 

However, the biggest issue is that the Tree of Heaven is able to suppress native plant growth through a process called allelopathy.

The Tree of Heaven (pictured) is native to China but is now spreading through the UK’s urban areas. Its roots are known to damage sewers, drains, and even building foundations 

The tree secretes toxins into the ground around itself, which prevents other plants from germinating or growing in the surrounding area. 

Currently, the tree is limited to a few urban areas of the UK, especially around train tracks in London, where it thrives.

However, as the climate gets warmer, scientists are concerned that the Tree of Heaven will be able to spread more widely throughout the country. 

Ragweed (Ambrosia) 

Ragweed, which originates from North America, is not toxic but can pose a health risk for people with hay fever.

A single ragweed plant is capable of producing one billion pollen particles in a season, peaking during autumn and summer. 

The pollen from this plant causes sneezing, itchy eyes, and can aggravate conditions like asthma and eczema. 

Scientists have previously warned that the health impacts of ragweed’s spread throughout Europe may be significantly underappreciated.

Ragweed (pictured) is a serious problem for hay fever sufferers since a single plant can release up to a billion pollen particles in a season, even triggering asthma in some cases 

One study found that allergies caused by the plant affect around 13.5 million people in Europe^[5], leading to health costs of £6.5bn every single year. 

Research also suggests that this impact is only going to get worse over time.

One study estimated that ragweed pollen concentrations will increase fourfold by 2050.

To make matters worse, scientists have warned that ragweed will spread more quickly as climate change leads to rising temperatures and increased CO2 concentrations in the atmosphere.  ^[6]

Invasive species: The animals, plants and microbes brought into regions that aren’t their own^[7]

An invasive species is one – be it animal, plant, microbe, etc – that has been introduced to a region it is not native to.

Typically, human activity is to blame for their transport, be it accidental or intentional.

Hammerhead flatworms have become invasive in many parts of the world. They feast on native earthworms, as shown

Sometimes species hitch a ride around the world with cargo shipments and other means of travel.

And, others escape or are released into the wild after being held as pets. A prime example of this is the Burmese python in the Florida Everglades.

Plants such as Japanese knotweed have seen a similar fate; first propagated for their beauty in Europe and the US, their rapid spread has quickly turned them into a threat to native plant species.

Climate change is also helping to drive non-local species into new areas, as plants begin to thrive in regions they previously may not have, and insects such as the mountain pine beetle take advantage of drought-weakened plants, according to the National Wildlife Federation^[8].