In 1852 German botanist Phillipp Franz Von Siebold introduced an exciting new plant species to the United Kingdom called Japanese Knotweed, featuring thick bamboo-like canes and resembling Russian vine in its foliage, it was an instant hit. The Royal Horticultural Society cultivated samples and sent them out to land owners, whilst the Railway saw it as the perfect plant to sure up the banks of their expanding rail network. Unfortunately with time this hero species turned to villain as it spread far and wide and began to cause irrepressible damage to land and property. Japanese Knotweed found itself on a long list of non-native and undesirable invasive species, which includes Rhododendron, Grey Squirrel, Canada Goose and many more.
Under the Wildlife and Countryside Act 1981, it is an offence to plant or encourage the growth of Japanese Knotweed in the wild, but despite efforts to curb it, the plant remains present throughout the UK including within the South Cliff Gardens.
It’s an incredibly tenacious species which can grow up to an alarming 2 meters in just 30 days, as little as one centimetre of root can generate a new plant and it can grow both under and above ground. One of its most challenging features is its strength, it can penetrate hard substances such as tarmac and concrete. This obstinate plant is often compared unfavourably to the fictional Triffid but fortunately for us this may be a little unfair as amongst its arsenal of antisocial traits it stops short of being either independently mobile or carnivorous!
Our garden team continue to work to eliminate this species from the gardens and are vigilant about identifying occurrences. You may have noticed areas of the gardens which are cordoned off, this is to both prevent spread and allow for treatment. Its presence is also one of the reasons we ask that dogs are walked on lead, fortunately the plant is not harmful to animals but it is possible that our canine companions could encourage its spread if they dig it up.
With hindsight we wouldn’t have introduced this plant to the UK but in its native countries it is viewed in a very different light, as a useful species which has been used for centuries in traditional medicine to cure a wide range of ailments, from bronchitis to skin disease. Ongoing research suggests that it may have dental benefits including reducing plaque and gum swelling and may be effective in treating gingivitis when used as a mouthwash.
It is edible and is said to resemble a slightly lemony rhubarb in taste, it’s also a bit of a nutritional powerhouse containing the vitamins A and C as well as potassium, zinc, phosphorus and manganese. It is a late bloomer and its small white flowers are a favourite with bees, the nectar they collect can be cultivated into knotweed honey, which is high in anti-oxidants.
However, a note of caution before you reach for the secateurs, it is not recommended for consumption in this country due to the possibility that it may have been treated with herbicides and by foraging it you could fall foul of the law, as it is illegal to remove knotweed for any other purpose than disposal at a registered landfill. So it’s not a plant that’s likely to become a staple on British menus any time soon and is best left to the professionals to deal with.
Gemma Alexander – Community Engagement Officer