Plants Mistaken for Japanese Knotweed
I have been compared to many other people in the past, Harrison Ford, David Duchovny, Bono, Robin Williams, and, my personal favourite, Daniel Craig. I must just have one of those faces I guess. Unfortunately, I’m not as good looking, talented, funny, or wealthy as any of the afore-mentioned celebs. Now this leads me on to consider a famous (or infamous) celebrity of the plant family, Japanese knotweed. This poor plant which, in its native land does no more harm than a wood-bug, over here in the UK (and the rest of Europe and the USA) has been transformed (some would say hyped) into a monster of the natural world.
There aren’t many people out there who will profess to like this perennial plant, and few people would blame you for wanting it gone, especially if you are a home owner looking to sell. But it is important to be accurate with Japanese knotweed identification, if only to avoid attacking some other innocent shrub with herbicide. We’ve discussed previously the easy-to-spot visual clues to identifying Japanese knotweed, so in this article we’ll consider a few of the plants mistaken for Japanese knotweed (and a few examples that look nothing like knotweed but still, somehow, get confused for it).
Also known as Pheasant Berry and Himalayan honeysuckle, this beautiful plant has the habit of seeding itself all over the place. However, it can’t really be described as invasive and isn’t a ‘Scheduled’ plant. The image on the left below shows how, at first glance, it could be confused with Japanese knotweed. Looking at the close up photo, however, brings out the differences, the most obvious being the leaves growing in pairs along the stem (Japanese knotweed leaves grow alternately). Nothing to be scared of, just look out for seedlings each year.
Broad leafed dock
Looking at the photo above tells you all you need to know about this commonly misidentified weed; it looks nothing like knotweed! What you can’t see here though is the newly unfurling leaves, which do so in a manner very similar to Japanese knotweed. Dock grows as a multi-leaved plant from individual tap roots and will commonly reach a metre in height with its central flower spikes. Japanese knotweed will normally reach at least two metres in height, with many leaves growing from each main stem and side shoots.
This garden favourite is often a plant mistaken for Japanese knotweed, with its spade shaped leaves and lush green foliage. Although it will send up lots of annoying little suckers if chopped back, that is the extent of its invasive capabilities. Woody stems give this one away (this one is a really quick and easy identifier) as opposed to the hollow stems of Japanese knotweed. So don’t go spraying your lilac bush – spring will bring thousands of beautiful, fragrant white or lilac (of course!) flowers.
Bindweed has to be one the most annoying weeds ever. Give it half a chance and it will climb through all your favourite shrubs and become entangled with every branch, stem and leaf, reaching up to the light by literally wrapping its thin stems around anything that’s available. It’s this characteristic that makes it such a pain to remove – ripping the bindweed stems out often damages any soft stems and leaves on the host plant as well. If you have a lot of patience, you can unwrap each entangled stem all the way down to ground level, where you can then locate and pull out the roots. Again, it’s the leaf shape that makes bindweed look a bit like Japanese knotweed. Look carefully at the leaves and you’ll see that they are heart shaped, with lobes either side of the stalk, which Japanese knotweed does not possess.
It would be difficult to mistake Bamboo for Japanese Knotweed. Japanese knotweed shoots look a bit like bamboo stems but there the visual similarity ends. Japanese knotweed leaves and bamboo leaves are not the same shape at all and knotweed loses its leaves in late autumn, unlike bamboo which usually retains its leaves all year round in the UK. Many bamboos (particularly running bamboo varieties) will migrate outwards and, because the rhizomes of Japanese knotweed also the method by which it spreads, this may be a factor in the two plants being confused.
The name ‘Mile-a-Minute’ might give you some idea of how quickly this vine-like perennial grows, quickly swamping most other plants in the area. It’s closely related to Japanese knotweed – these two darlings can actually create hybrids – but doesn’t have the same fearsome reputation. The leaf shape and flowers are very similar, although the leaves are more arrow-shaped than Japanese knotweed leaves. The lack of tall stems and its scrambling, untidy habit are dead giveaways.
Houttuynia are perennial plants with orange-scented, heart-shaped leaves and small white flowers. The illustration here gives a hint to why houttynia can be mistaken for Japanese knotweed. Although it can easily spread through its rhizomes (it loves moist soils) it generally only reaches 30 centimetres in height. Compare that to Japanese knotweed which grows to three metres tall in the right conditions and it’s clear that the comparison ends there.
This is just a sample of the plants we’ve been asked to identify by customers worried about the possibility of Japanese knotweed on their property. PBA Solutions can help you with our free ‘ID My Weed!’ invasive weed identification service and help with the identification of plants mistaken for Japanese knotweed. Click the link and send us some photographs (close-ups are preferable) of the suspect plant, including any additional details and your name and telephone number. We will do our best to identify the weed for you.
PBA Solutions undertake site surveys to determine if Japanese knotweed is present and document and report on the findings. You can book a Japanese knotweed survey here. Our reports integrate with the mortgage process and site developments, detailing the most appropriate Japanese knotweed solutions.
For further help and information concerning plants mistaken for Japanese knotweed, call our friendly team on 0203 174 2187 or 01202 816134.