Understanding the difference between Japanese knotweed and Chinese knotweed starts with identifying the characteristics of each

The difference between Japanese knotweed and Chinese knotweed is not immediately evident. Both plants have a bamboo-like trunk, green leaves that turn brown in the fall, flowers with yellow petals around this time of year as well.

The only way to tell them apart is by looking at their roots: one species has edible white rhizomes while the other has poisonous black ones!

Knotweeds are a common sight in the natural landscape, but some species have evolved to be much more difficult than others.

Chinese and Japanese Knotweed both grow quickly from their seeds which can spread rapidly through dry soil or on dunes where they take over almost completely due to an aggressive growth habit that doesn’t allow other plants room for survival .

As with most knotweeds which are perennials and can be found along the railway lines, riverbanks, pavements, and roadways, knowing the difference between Japanese knotweed and Chinese knotweed is seen in the characteristics of each plant. 

Both these plants reproduce easily through their root system, stems, and rhizomes. The knotweeds are extremely aggressive; they can grow so fast in undesirable places.  The plants closely resemble each other, which makes it harder for one to identify them properly.

This article describes the difference between Japanese knotweed and Chinese knotweed. Better understanding will allow you to appreciate that not all weeds are bad.

What is Japanese knotweed?

Japanese knotweed is native to East Asia. The weed is aggressive and has the potential to cause damage within a short period. The plant thrives in all climatic conditions and is spread through fragments of root, stem, and crown cuttings.

This invasive knotweed produces new shoots each year from the rhizomes, buds, or crowns. The shoots begin appearing in mid-spring to the last weeks of summer. The stem becomes hollow when mature. These plants can grow up to 10 inches per day after emergence. They flower from the last weeks of summer to early autumn.

The weed grows largely on the roadsides, riverbanks, railway lines, and even in properties. Several plants are often mistaken for Japanese knotweed. One such plant is the Chinese knotweed.

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What is Chinese knotweed?

Chinese knotweed (persicaria Chinensis) is commonly referred to as creeping smartweed. It belongs to the family of Polygonaceae. A common plant in China, Vietnam, and Malaysia, where it is used as herbal medicine.

The Chinese knotweed belongs to the buckwheat family. It is mainly found in China. Unlike the Japanese knotweed that is invasive and destructive, the Chinese knotweed is cultivated for medicinal purposes.

Chinese knotweed looks similar to Japanese knotweed. The subtle differences are both the size of the leaves and the flowers - difference between japanese knotweed and chinese knotweed
Chinese knotweed looks similar to Japanese knotweed. The subtle differences are both the size of the leaves and the flowers

Difference between Japanese knotweed and Chinese knotweed

The Chinese and Japanese knotweeds are similar in a way; this causes major confusion. Here are the major differences in the plants’ characteristics.

1.     Leaves

The leaves of the Japanese knotweed are dark red and measure about 4 cm long. The young leaves are usually rolled up and featured dark red veins. The leaves become heart-shaped when mature and weigh about 12 cm long.

The Chinese knotweed leaves are simple and alternate, measuring about 2 cm long. Their margin is long and wavy, the upper side is smooth, while the lower side is hairy. The leaves’ venation is marked and consists of several parallel arched ribs. The blade is green with a dark spot in the centre.

2.     Flowers

The Japanese knotweed flowers are creamy-white in colour and measures 0.5cm wide. They form clustered spikes of flowers in the dense foliage; the length of the spikes is about 10cm.

The Chinese knotweed flowers appear between November and March. A short pedicel supports them at the base, which is full of foliage. The flowers are small and pink or white. They measure about 2mm with  8 stamens and 5 tepals characterized by purple tips.

3.     Fruits

The Japanese knotweed does not produce fruits of any kind. On the other hand, the Chinese knotweed produces achene trigonous that are 4mm long bluish-black. They are covered by large succulent blue-black persistent perianth.

4.     Roots

The Japanese knotweed roots are dark brown on the exterior and orange in the inside, those of the Chinese knotweed is irregular and measure about 15 cm long in diameter. The roots are reddish-brown, they appear wrinkled and consist of transverse and longitudinal lenticels.

Chinese knotweed dried out is used extensively in medicine
Chinese knotweed dried out is used extensively in medicine

Chinese knotweed therapeutic uses

As mentioned earlier, the Chinese knotweed is cultivated in most parts of the world for medicinal purposes.  The plant is prepared by drying the tubers. They are then boiled in water and consumed as a tea. Here are some of its benefits:

1.     Aids indigestion

The Chinese knotweed contains stilbene glycosides, which is a laxative and anti-oxidant compound.  The compounds can successfully get rid of cholesterol and detox the body when taken regularly.

2.     Immunity Booster

The weed has been effective in elevating the immunity system by eliminating toxins and renewing the body cells regularly.

3.     Heart health

The Chinese knotweed contains lectins that attach to the carbohydrates in the cells of the body. These factors are responsible for helping decrease plaque in the small blood vessels. In addition to that, the knotweed can lower blood cholesterol, thus enhancing cardiovascular health.

4.     Muscle recovery

 Chinese knotweed is perfect for muscle growth and tissue recovery. This makes this plant ideal for fitness enthusiasts, weight lifters, and bodybuilders.

5.     Hair growth

This knotweed has been used for several years among the Chinese people. This weed contains a chemical compound called Radix polygon Multiflori which comes with hypolipidemic effects. These agents help reduce cholesterol in the body. Furthermore, they revitalize hair and help in bone density.

6.     Anti-inflammatory agents

Knotweed can prevent pro-inflammatory pathways. The knotweed has bioactive substances that effectively control inflammatory diseases.

7.     Blood enhancer

The Chinese knotweed boasts a significant amount of iron as compared to other plants or legumes. Iron is a key nutrient in making the red blood cells in the body.  The plant has lecithin that helps in the composition of the nerve tissue, which in return boosts the red blood cell membranes.

Its components also help in blood clotting, a mechanism that is vital in the human body. Without the blood clotting process, there is a risk of a heart attack resulting from blood clots in blood vessels.

8.     Enhancing sleep

Insomnia is a common sleeping disorder that refers to the inability to fall asleep naturally. To induce sleep, the drug has to target the melatonin receptors, serotonin, and GABA receptors. The Chinese knotweed, when taken in recommended quantities, helps combat insomnia without side effects.

Dry knotweed or Polygonum aviculare on a wooden spoon and used within Chinese medicine
Dry knotweed or Polygonum aviculare on a wooden spoon and used within Chinese medicine

Side effects of Chinese knotweed

There are no serious side effects associated with the intake of this drug. The most common mild effect is a gastrointestinal disturbance, which is quite common with most herbal medicine.

Conclusion

There are two types of knotweed – Japanese and Chinese. The key difference between the two is that Japanese knotweed will grow in wetter conditions, while Chinese grows best when it’s dry.

However, both can spread quickly once they take root so if you have either type on your property we recommend contacting a professional for help with removal and containment.

Just like Chinese knotweed, several other plants look like Japanese knotweed. These plants do not necessarily have all the features of the Japanese knotweed, but they are similar in a way that can lead to confusion.

In conclusion, Chinese knotweed is not the same as Japanese Knotweed. There are some differences to be aware of before taking action with your weeds in order to protect yourself from any potential legal trouble or fines.


Want to know more?

Knotweed Removal aims to provide the most up to date information, help and advice for YOU to make informed decisions. If you are unsure or uncertain on how to proceed, please reach out to us and we will gladly come back and advise you as best we can.

Governmental advice can be found here and the UK law covering the removal of Japanese Knotweed as stated under the Wildlife and Countryside Act 1981 can be found here.

The best means to contact us is via our email – knotweedremovaltips@gmail.com

Do not forget we have a library of blogs covering many areas relevant to Japanese Knotweed, our free downloadable How-to Guides and Product Reviews on the latest methods being employed to eradicate or remove Japanese Knotweed.

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