Identification
Japanese Knotweed
Japanese Knotweed is a distinctive plant and early identification is essential to prevent further contamination. The weed assumes various states through the year which can make it difficult to identify. To the untrained eye it can seem quite unassuming, even pleasant.
Identifying Characteristics
 | At full maturity the leaf is oval shaped with a pointed tip. Underneath the leaf are distinctive reddish veins. Green in colour through the Spring and Summer the leaves turn brown in the Autumn. |
 | From the main stalk leaves grow in a zig-zag pattern. These smaller leaf stems are often quite red. |
 | White and cream in colour these flowers appear in late Summer or early Autumn. Distinctively they hang in drooping clusters from the stalks. The flowers turn reddish in the Autumn. |
 | In early Spring a young stalk is reddish and shaped like asparagus; until later when the leaves unfold. In late Spring and Summer it becomes a thick cane and is a vibrant green with purple specks. The cane is bamboo-like in appearance. In the Winter the canes lose their colour and turn woody. |
 | The rhizome of Japanese Knotweed is the underground stem that stores the nutrients for the plant to grow. Dark and leathery in appearance on the outside, the Rhizome is often bright orange and yellow with a rusty colour at the core. When snapped, they make a sound like a carrot breaking. |
Seasonal Features
Spring
The first signs of Japanese Knotweed growth are distinctive red and purple shoots. These are often accompanied with rolled back leaves which grow rapidly from the stored nutrients in the rhizome.
Summer
The stem resembles bamboo, though more green in colour with purple speckles. Inside, the cane has distinctive chambers that retain water and nutrients. The leaves have pointed tips that extend from the stem in a zig-zag pattern. Later in the season, creamy-white flowers hang in clusters from the stalks.
Winter
As the first frost appears, the plant's leaves turn brown. During this period Japanese Knotweed withdraws back into its rhizome. The canes lose colour and turn into woody stalks which can take years to decompose. New shoots can be found growing through the dead canes in the early Spring.
