Conservation charity Plantlife has issued some information about Japanese knotweed following research which showed that less than 20% of the population could identify it growing near their property or in their garden.
Getting it wrong can be expensive – the plant can penetrate cracks in brickwork and concrete and has roots that can grow down as far as 9 feet, and out 21 feet in all directions – and getting rid of it can cost up to £15,000. Plantlife advise to look for lush green heart-shaped leaves on zig-zag purple-speckled stems. The rhizomes, the horizontal roots that produce the white shoots, are bright orange when cut open. In spring reddish purple shoots emerge from ground level crimson buds, and grow into bamboo-like canes flecked with purple and with cream-coloured flowers. These canes die back to ground level in the winter.
In a recent court case two homeowners in South Wales successfully sued Network Rail after knotweed spread from a railway embankment to the foundations of their houses. This made them unsalable, as banks and building societies won’t give mortgages on properties with a knotweed problem. However this could change as recent research by the University of Leeds and infrastructure services firm AECOM shows that the invasive plant very rarely causes structural damage and in any case less than trees, climbing plants and shrubs such as buddleia growing near buildings.