The Saga of the Japanese Knotweed

The Saga of the Japanese Knotweed

Japanese Knotweed

“Fleeceflower” or “September Mist,” are names that will certainly evoke warmth and beauty or the gentle and charming, mild, shadowy days of September. However, given the sheer tenacity and unstoppable nature of this plant it is often known by other more descriptive names like Mile-a-Minute. Meet the Japanese Knotweed.

Having arrived in Canada in the nineteenth century, it has gradually made its appearance in every province except Saskatchewan and Manitoba. It’s likely only been in Newfoundland since some time in the twentieth century, probably the latter half of it. While at one time, this persistent plant was welcomed. Now, a century and a half later, as far as some are concerned, the knotweed is virtually taking over. The mood has dramatically changed. Now most just want to be rid of it. Still, some say, well, just hang on a minute.

Origins of the Knotweed

If you’re looking for its origins, you need to cast your eye to, as you might expect, the slopes of a volcano in Japan as well as in other countries in the southeast of our great planet. Beginning in the nineteenth century, individuals with an eye to the so-called exotic encountered these plants and thought they would make a beautiful addition to the gardens in their home countries of Britain and the United States. One Philipp Franz von Siebold, a European adventurer discovered this plant carpeting the exterior of a Japanese volcano and proceeded to transport it first to Leiden in the Netherlands. He then gave a good-hearted gift to the Royal Botanic Gardens, Kew in Britain. Soon, anyone who was anyone gathered the Japanese knotweed into their arms throughout Britain as a popular ornamental plant and the rest is history. Likewise, by the late nineteenth century, this plant completed its journey to North America.

Here to Stay

The problem is that the Japanese knotweed has done exceptionally well in the numerous countries where it has now made a home for itself. The purple to green stems of this plant are hollow with raised nodes, giving it the appearance of bamboo (to which it is actually not related). These stems die back each autumn and in the spring, they go on to re-grow to a maximum height of around 3-4 m (10-13 ft) in a single growing season. They apparently accomplish this at up to 8 cm per day. That’s not bad. If they are continually cut back, of course, this will impede their growth expectations. But left alone, they’ll reach 1 metre in three weeks. The leaves are generally quite broad (5-12 cm/2-4 ½ in) and long (7-14 cm/ 3-5 ½ in). By Autumn, delicate and small cream or white coloured flowers begin to appear.

Regardless of their beauty, many focus on the difficulties of being rid of the Japanese Knotweed. Apparently, they’re gifted with a root system that is intended to withstand the worst.

To make matters worse for the individual trying to eradicate them, they are equally gifted with a tolerance for a wide range of soil types, pH, as well as salinity. And just in case someone thought a good reduction in temperature would do the trick. Their rhizomes, sort of a creeping root stock, can survive temperatures of -35 °C (−31 °F) while extending 7 metres (23 ft) horizontally and 3 metres (10 ft) deep. The roots are strong, too, with asphalt and concrete posing no great obstacle for them. So, not only are they a hazard to a gardener guarding their plot, buildings and roadways also must beware. And while some may utter a poetic remark regarding their beauty or at the very least their obvious hardiness, others have one word for them—invasive.

Get the Invaders

In fact, they’re considered by the International Union for Conservation of Nature to be one of the world’s 100 worst invading species. One can understand the frustration. It’s a plant we haven’t been able to control and that’s often a sticking point for humans. However, it depends on how one views the world. Despite all the variations in the qualities of climate, soil or water that covers our beautiful world, if we think of the planet as a whole, there can be no invasion. Much as humans did in our early years, moving out of Africa, at the time, there were no designated boundaries to brand us as an invasive species. If there had been, that’s what we would’ve been. So, from this perspective, Japanese Knotweed have merely moved on (with our help) and the goal is to find a way to live with that reality.

What About in Japan?

Some may say they’re obviously from Japan, what do they do? Well, in Japan, nature herself takes care of it, for where the knotweed resides keeps it in check. First of all, growing as they do on the scree of a volcano naturally impedes their growth. So, while they may be lush and rich in places such as Newfoundland and Labrador, they tend to be much smaller in their native land. Japan also presents a slightly more hostile environment and so the Japanese knotweed must contend with large herbs such as Bamboo, in addition to various natural pest, soil fungi and plant diseases. They’re kept in control.

In certain parts of Britain, efforts have been underway to adopt some of these natural checks. The insect known as Aphalara itadori is one of about 186 species of insects that feeds on the Japanese knotweed in Japan. In Britain as well as the United States, they have tested a range of insects known to control the knotweed in Japan. Unfortunately, the findings discovered the insects may well become a danger to their own native plants. So, thus far, everything but the A. itadori have been rejected. However, while many pinned their hopes on A. itadori, Scotland, for one. has passed a law stating now it is illegal to introduce a non-native species. Obviously, we’re going to have get a little more creative in our solution to the Japanese knotweed.

If you Can’t Beat it, Eat it”

Some in Newfoundland are adopting the approach of many in Pennsylvania and have ceded defeat in eradicating Japanese Knotweed. Instead, they have decided it is better to wield knife and fork to at least come to terms with the unstoppable plant. If they are to a part of our diets, the general rule is to treat knotweed much as one would when using rhubarb or asparagus. The younger shoots are the easiest to use as they can be harvested by easily snapping or cutting them off at ground level when they are a mere few inches in height. They tend to send up multiple shoots during the spring and early summer, so tjat makes things a little easier for the knotweed aficionado. One word of warning. They are fairly high in emodin, a known laxative, so take care. Plus, they contain oxalic acids and anyone with or predisposed to kidney stones should probably give them a wide berth. Otherwise, they are a healthy option for food, not to mention for their medicinal attributes.

Japanese knotweed contain resveratol which is also found in grape skins and wine and they’re noted for herbal actions such as being antibacterial, antiviral, anti-spirochetal, immunostimulant, anti-inflammatory, central nervous system relaxant, brain and spinal cord protectant, anti-carcinogenic, vasodilator, cardioprotective, antithrombotic, hemostatic and astringent (see Stephen Buhner’s book Healing Lyme: Natural Prevention and Treatment of Lyme Borreliosis and Its Coinfections, published in 2005. An updated version is now available.). According to Buhner, Japanese Knotweed is useful against Lyme Disease given its ability to strengthen the body’s immune function.

It is also hoped to be able to play a role as an angiogenesis stimulant, being able to form new blood vessels (angiogenesis). As a result, it can play a role in the healing of damaged blood vessels, for instance with burns, chronic inflammations such as rheumatoid arthritis, macular degeneration, and brain disorders like strokes and other forms of heart disease.

Leaving aside its value as a foodstuff or for its medicinal properties, Japanese knotweed also functions well geographically. With its substantial root system, it works wonders at preventing erosion. When the knotweed has grown, people have also discovered they function as a useful hedgerow.

So, it seems the knotweed does have some uses if we employ a little creativity and understanding. We had little to do with how it got to Newfoundland, but it’s here now. Like the multitude of plants and animals, ourselves included, who have moved around endlessly on this planet, they really have every right to be here. There’s nothing to lose, so you might as well fasten on your bib and enjoy what the knotweed has to offer.


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