Plants That Look Like Knotweed
PLANTS THAT LOOK LIKE JAPANESE KNOTWEED
What does Japanese Knotweed look like?
Japanese knotweed can be identified through its heart shaped leaves that appear in early spring. In summer, small white flowers may appear, and as we head into winter, the leaves will fall and brown stems will be left behind.
When looking to identify Japanese knotweed by its stems, they are predominantly green with reddish specks and a reddish tint.
For a good look at what Japanese knotweed really looks like, take a look at our Japanese Knotweed photo gallery.
Russian Vine (Fallopia baldschuanica)
How Russian Vine looks similar to Japanese Knotweed
Sharing the same Latin genus of Fallopia (Japanese knotweed is Fallopia Japonia), Russian vine and Japanese knotweed are probably confused the most. Also a fast-growing plant, Russian vine sprouts leaves and flowers that can present very similarly to Japanese knotweed. Nicknamed ‘Mile a minute’, Russian vine grows in a disorderly manner and quickly takes over an area.
The differences between Russian vine and Japanese knotweed
- Much like bindweed, Russian Vine relies on other plants or solid structures to climb up and cannot support itself.
- Russian vine also grows in a more disorderly manner than Japanese knotweed and looks untidy comparatively.
Bindweed (Convolvulus arvensis)
How bindweed looks similar to Japanese knotweed
With its heart-shaped leaves that alternate along the stem, Bindweed may look similar to Japanese knotweed. Also, much like knotweed, when it appears in spring, Bindweed can cover a large area very quickly.
Differences between bindweed and Japanese knotweed
- Large, white or pale pink trumpet shaped flowers appear in spring. Japanese knotweed won’t flower until later in the year and has small, delicate white flowers.
- It grows on top of other plants or along the floor as it’s not self-supporting. Japanese knotweed, on the other hand, grows from strong stems.
- It has very pointed leaves in an extended heart shape whereas Japanese knotweed leaves have a softer heart shape.
Himalayan Balsam (Impatiens Glandulifera)
How Himalayan Balsam looks similar to Japanese Knotweed
Just like Japanese knotweed, Himalayan Balsam is a fast grower; it can quickly cover a large area and grow as tall as 2.5 metres in height. And, also like Japanese Knotweed, it has a hollow stem.
The differences between Himalayan balsam and Japanese knotweed
- Himalayan balsam has vibrant pink flowers that are seed producing, whereas Japanese knotweed has smaller white flowers.
- Himalayan balsam will tend to frequent water courses, which Japanese knotweed may do, although it’s more commonly found in residential areas.
- It spreads through seed pods, which explode when touched or when mature, and can spread seeds up to seven metres away. Japanese knotweed spreads through its hardy root system.
Bamboo (Running and Clumping Types)
How Bamboo looks similar to Japanese Knotweed
The main reason people confuse Japanese knotweed with bamboo is because of the stems, or culms. These parts of the plants can look similar if the Japanese knotweed has not produced any leaves yet.
The differences between bamboo and Japanese knotweed
- Bamboo tends to only produce leaves at the top of its stems, whereas Japanese knotweed will produce them all along the stem.
- If the bamboo is a clumping variety, it will only grow in one spot and won’t spread that quickly, whereas Japanese knotweed certainly will.
- Bamboo stems come in all sorts of different colours, from gold to black and green. Japanese knotweed stems will always start life as a reddish-purple colour and grow into a green and red stem.
Broad-leaved Dock (Rumex obtusifolius)
How broad-leaved dock looks similar to Japanese knotweed
Broad-leaved dock is from the same family as Japanese knotweed, so, it’s hardly surprising that it looks similar. Broad-leaved dock has leaves arranged alternately along the stem, and its stems form spikes just like Japanese knotweed. In winter, broad-leaved dock also has similar brown canes left behind, which is often when it is most commonly mistaken for knotweed.
The differences between broad-leaved dock and Japanese knotweed
- Broad leaved-dock stems are fluted and shorter than Japanese knotweed plants, growing up to 1m in height.
- Additionally, broad-leaved dock stems are not completely hollow and contain a foam-like substance when snapped open.
- The flowers of broad-leaved dock are red and look more like berries.
Himalayan Knotweed (Persicaria wallichii)
How Himalayan Knotweed looks similar to Japanese Knotweed
As part of the same knotweed family, and sharing a similar name, it can be easy to mistake Himalayan knotweed with Japanese knotweed. With a very similar stem to Japanese knotweed, it can easily be mistaken when not in bloom. You’ll also find that it has a hollow stem, like knotweed and that the leaves are alternately arranged along the stem too. Both types of knotweed spread in the same dense way as well.
The differences between Himalayan knotweed and Japanese knotweed
- You can easily tell the difference by the leaves, which on Himalayan knotweed are very narrow, often half as wide as they are long.
- On closer inspection, you’ll also note that the stem is much thinner, growing to around 1cm in diameter.
- The flowers on Himalayan knotweed have a pink hue, which distinguishes them from the pure white of Japanese knotweed’s.
Himalayan Honeysuckle (Leycesteria formosa)
How Himalayan Honeysuckle looks similar to Japanese Knotweed
As part of the same knotweed family, and sharing a similar name, it can be easy to mistake Himalayan knotweed with Japanese knotweed. With a very similar stem to Japanese knotweed, it can easily be mistaken when not in bloom. You’ll also find that it has a hollow stem, like knotweed and that the leaves are alternately arranged along the stem too. Both types of knotweed spread in the same dense way as well.
The differences between Himalayan knotweed and Japanese knotweed
- You can easily tell the difference by the leaves, which on Himalayan knotweed are very narrow, often half as wide as they are long.
- On closer inspection, you’ll also note that the stem is much thinner, growing to around 1cm in diameter.
- The flowers on Himalayan knotweed have a pink hue, which distinguishes them from the pure white of Japanese knotweed’s.
Houttuynia (Houttuynia cordata)
How Houttuynia looks similar to Japanese knotweed
Much like Japanese knotweed, houttuynia is a perennial plant with heart shaped leaves and delicate white flowers. It spreads through a rhizome system and grows at similar times and in similar ways as Japanese knotweed, meaning it’s easily mistaken.
The differences between houttuynia and Japanese knotweed
1. The houttuynia flowers are orange-scented, something that can’t be said of Japanese knotweed
2. Houttuynia flowers have a yellow stigma at the top, which is where the pollen comes from.
3. Houttuynia is also much shorter than Japanese knotweed, as it won’t grow above 30cm. Japanese knotweed can easily grow above 2.5m.
Need help identifying the weed you have?
send us a photo of your suspected Japanese Knotweed
and we’ll identify based on your image.
Whether you want a no-obligation visual identification or have confirmed you have Japanese knotweed,
contact Japanese Knotweed Specialists or give us a call on 0800 122 3326.
