Introduced in the 19th century as an ornamental garden plant, Japanese Knotweed is now considered a blight on Scottish landscapes, threatening native plant species and wildlife, and causing problems for home owners.

Network Rail has been accused of failing to properly treat Japanese Knotweed on their land, negatively impacting adjoining home owners who are struggling to sell.

Figures obtained by The Times newspaper show that of more than 6000 UK-wide complaints to the government-owned company, the most came from Glasgow at 569. Edinburgh, Kilmarnock, Paisley and Motherwell also had significant issues.

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The number of complaints levied at Network Rail increased by 70 per cent between 2012 and 2018.

A Network Rail Scotland spokesman told The Herald: "We monitor the growth of knotweed on our infrastructure and once aware of any site where the plant is present we begin a treatment regime to remove it."

Difficult to to remove, either by hand or with pesticides, due to its tenacity, the plant can take a several years to die off completely. The Wildlife and Natural Environment (Scotland) Act 2011 came into force in 2012, making it an offence to knowingly, or unknowingly, spread Japanese Knotweed.

The large perennial has a vast network of hardy roots, rhizomes, that spread rapidly and are said to cause damage to building foundations and structures, crack concrete and block drains.

Mortgage lenders have been known to refuse mortgages for properties where the plant occurs.

Beth Stevenson, director of the Glasgow Mortgage Company, said she had seen a rise in cases of Japanese Knotweed preventing house sales:"We are hearing more of it and some of the lenders are just terrified of it.

"If you're considering buying a property with Japanese Knotweed you need to be 100 per cent sure it had been dealt with because it will devalue the property or make it difficult to sell in the future.

"If you're a seller, you need proof, usually with a five-year treatment plan, that you have dealt with it. If it has just been cut back or disguised it will just come back even worse."

Dr Peter Fitzsimons, invasive weed control group technical manager of the Property Care Association (PCA), said: "Effective eradication control of Japanese knotweed is a job for the experts and the earlier that work takes place the better.

"Currently, there is no legal imperative to remove or manage Japanese knotweed infestations as long as they are not causing a nuisance to adjoining properties or on land due for development."

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A 2018 study carried out by the University of Leeds and global infrastructure services firm AECOM claimed the weed rarely causes significant structural damage and that automatically refusing a mortgage is out of proportion to the risk posed.

Land beside railway tracks, rivers and canal networks have ideal conditions for the plant to flourish and can be hard to access, allowing the weed to thrive.

Scotland's native species are under threat from the invasive import, which can grow up to10cm a day, that dominates river banks and railway tracks.

However, the Scottish Invasive Species Initiative (SISI) is fighting back, training volunteers to treat Japanese Knotweed, Giant Hogweed and Himalayan Balsam in a bid to reclaim the landscape for native plants.

Herbicide is injected into individual stems but one treatment is not enough, and regular doses are required to eradicate the plant.

The four year project works with fisheries in the north of Scotland and aims to arm volunteer anglers, dog walkers and conservationists with the tools to continue the fight against the weed.

SISI communications officer Vicky Hilton said: "Japanese Knotweed out-competes all of our native flowers and shrubs so where you've got it growing, you've got no native flora growing underneath it.

"It's completely changing the habitat of the riverbank and that changes the insects that come and changes it for the small mammals around it.

"The best way to treat it is with herbicide so you're not getting any drift or damaging any flowers next door to it."