Accredited experts in Japanese knotweed identification, we’ve produced this gallery of Japanese knotweed images to help you identify your potential infestation with confidence. The following gallery includes Japanese knotweed descriptions and images of the invasive plants’ stems, flowers and leaves.
Unsure if you’ve got Japanese knotweed? Send us images of your potential infestation via our identification form at the end of the page and we’ll identify if it is Japanese knotweed for free.
Japanese Knotweed Roots (Rhizomes)
Japanese knotweed roots are known to grow up to 3 metres deep and 7 metres horizontally underground, depending on the soil and weather. The outside of Japanese knotweed rhizomes (roots) are dark brown on the outside, orange/yellow on the inside and have a diameter of approximately 20 cm.
Japanese Knotweed Shoots
Growing in a zig-zag pattern, Japanese knotweed shoots (stems) are green in the spring before turning more purple with red speckles throughout the summer and into the early autumn. The shoots’ are hollow and can grow up to 2-3 metres in height – up to 2cm a day.
Japanese Knotweed Flowers
Often blooming in later summer, Japanese knotweed flowers are cream white, form in panicles and can grow up to 0.5cam wide. Japanese knotweed flowers can grow up to 10cm long and frequently are mistaken for being lesser knotweed due to their similar size and colour.
Japanese Knotweed Leaves
Heart-shaped and with smooth edges, Japanese knotweed leaves are bright green and have pointed tips. Extending up to 14 cm long, these leaves only survive the warm months of Spring and Summer.
Japanese Knotweed infestations
Below, we’ve provided images of Japanese infestations in various settings to showcase the different ways Japanese knotweed can spread. If you need to eradicate Japanese knotweed then check out our how to get rid of Japanese knotweed guide.
Japanese knotweed law
As Japanese knotweed legal experts, we have a history of helping victims of Japanese knotweed win compensation against sellers that have lied about knotweed and those that have Japanese knotweed spread from their neighbours Get in touch on the form at the side of the page to find out how we could help you win compensation.
Japanese knotweed seeds are heart-shaped and feature small wings. It’s extremely rare for seeds to germinate in the UK as only female plants have been recorded to date across Great Britain and Northern Ireland. Instead, new Japanese knotweed plants grow from nodes or pieces of its stem in soil or water.