Species of the Month: June 2017


Japanese Knotweed Fallopia japonica


© Peter Sturgess

Once planted as an ornamental plant in parks and gardens, Japanese Knotweed is now considered a dangerous invasive species in the UK, as it can cause damage to building and infrastructure. The species spreads agressively and can reproduce from just a small piece of root cut off. There are particular problems with the plant in south Wales, where large stands form along rivers and railways.

As well as causing economic problems through property damage, Japanese Knotweed is also bad news for native wildlife. The large fast growing plants will smother other plants, and offer little as a food or shelter source for other creatures. It is very important to record the species, so that proper control methods can be implemented. You can view the Welsh distribution here on Aderyn.

The species forms 2 metre high stands (similar to Bamboo) at this time of year, with large cordate leaves. More images and identification features can be found on NatureSpot. More information on Japanese Knotweed is available on the GB Non-Native Species Secretariat website.

If you spot Japanese Knotweed during June (or at any other time of year), please send us the record, ideally via our Species of the Month form on SEWBReCORD (nb. you will need to be signed into SEWBReCORD to use this link). Due to the tendency of the species to cover large area, we have the option to record a "patch" of Japanese Knotweed by selecting the polygon option on the map (middle icon on top right of map). Instructions on how to submit records are available here.