Japanese knotweed: An invasive plant posing environmental and structural threat

It spreads rapidly. Despite its initial appearance, it is exceptionally dangerous for the environment and infrastructure. A gardener explains how to recognize it.

Japanese knotweed, also known as knotweed, is an exceptionally aggressive species. It can reproduce vegetatively and spread quickly, which makes it extremely harmful to natural environments and crops. It can even penetrate concrete.

The International Union for Conservation of Nature has recognized this plant as one of the worst invasive species in the world. Its cultivation is legally prohibited in many European countries.

"Japanese knotweed can look fairly attractive with its creamy white flowers and heart-shaped leaves but it's extremely destructive to its surroundings. To a lot of novice gardeners, Japanese knotweed will look normal but it can cause a lot of damage to your home by eating its way through your walls, which is why it's important to be able to recognise it," warns gardening expert Chris Bonnett on gardeningxxpress.co.uk.

He points out that while many novice gardeners may find knotweed unassuming and not initially suspicious, it is extremely dangerous. "It can cause a lot of damage to your home by eating its way through your walls, which is why it's important to be able to recognise it," he advises.

There are several signs that you are dealing with this perennial. Firstly, look for red shoots that may resemble asparagus spears.

Secondly, leaves that turn a vibrant green and have a heart or spade shape with a pointed tip. Thirdly, small clusters of white or cream flowers appear late in the summer and early autumn.

It's also worth paying attention to the stems, usually hollow and bamboo-like, and the rhizomes, which form the underground part of the weed. If fresh, they break easily. Their outer side is dark brown, and the inner side is usually orange or dark yellow.