The main spread of these plants especially Japanese Knotweed through the UK has been through the watercourses, transport routes and infested waste areas. It is an invasive non-native plant and in the UK it has none of its natural pests, such as insects and fungi that feed off the plant to keep it at bay. This as well as its invasive and highly competitive nature has facilitated its spread through the UK
Japanese Knotweed spreads by means of its stems and rhizomes, new shoots can arise from tiny fragments, which is one of the reasons it can spread so quickly and is often so difficult to eradicate. The rate of spread is dependent on the density and composition of the soil but rhizome growth can extend 7m laterally and 2 to 3m in depth. Lengths of shoot can also reproduce new plants. The plant itself can reach a height of 3m. It has shield-shaped leaves which are flat at the base and are carried of zigzag stems. The stems are bamboo like sturdy, purple spotted and hollow with regular spaced nodes.
The plant flowers late in the season and are creamy white coloured and are formed in drooping clusters up to 12cm in length. In winter, the leaves die back to leave orange/brown coloured woody stems which can stay erect for many years. In spring new emerging stems are green to red/purple with rolled leaves that unfurl as the shoot extends. The plant grows quickly through nutrients stored in the rhizomes of up to 40mm per day. The underground rhizomes are thick and woody with a knotty appearance and when broken reveal a bright orange coloured centre.
Japanese Knotweed is a large, herbaceous perennial plant that is native to Eastern Asia, in Japan, China & Korea. It was first recorded in Great Britain in 1825, where it was brought over as an ornamental plant and became prized for its grand size and sprays of white creamy flowers.
By 1886 it was established in the wild and now it has become widely established in the British Isles.
Manningtree, Brantham Felixstowe Chelsmford
Braintree Clacton. Frinton Hadleigh Woodbridge