Wednesday, August 18, 2010

Japanese Knotweed

So I've been a busy bee lately and haven't been weeding my organic garden. And when I went out in the back yard this morning, what to my wondering eyes should appear but an army of enormous trees that resembled sugar cane or bamboo. Trees that had been tiny sprouty weeds just two or three weeks ago.

When I tried to take the clippers to them, I was amazed at the resistance. The bigger specimens - which were at least seven feet tall - had turned hard as a rock and I had to put some real strength and sawing motion into my use of the shears. You can't quite tell it in the photo below, but this stump is thick as a broomhandle:

Intrigued by its bamboo-like qualities and astonishing rapid growth, I did a little research online and soon determined that what I have here is an infestation of Japanese Knotweed (Fallopia japonica), also known as Polygonum cuspidatum, Crimson Beauty, Donkey Rhubarb, German Sausage Plant, Hu Zhang, Itadori, Hancock's Curse, Japanese Bamboo, Himalayan Fleece Flower, Japanese Polygonum, Kontiki Bamboo, Mexican Bamboo, Peashooter Plant, Renouée du Japon, Reynoutria Fleece, and Sally Rhubarb.

It was brought from Japan to the UK in 1825 as an ornamental plant for gardens and was imported to the USA at some point soon after. In these new habitats the plants grew rapidly out of control, lacking the natural insect enemies that it has in Japan.

As it turns out, F. japonica is on the Worst Invasive Species List and is considered a major world problem. So much so that in the UK, it is illegal to deliberately cultivate it. According to Wikipedia, the U.S. Government will actually assist in eradication of the plants on your property via pesticide. Obviously, since I'm opposed to pesticides - especially in my organic garden - that's not an option for me.

In fact, the more I learn about this plant, the more I'm liking it. Like Bamboo, it has an indomitable will to survive and perpetuate itself via a complex grid of deep underground rhizomes that are nearly impossibly to fully eradicate. Figures vary from source to source, but reportedly the root structure of just one plant can survive temperatures of −35 °C (−31 °F) and can extend at least 10 feet deep and 23 feet wide. Therefore, considering I have an entire battalion of them in my back yard, it's safe to say that there must be an immense and amazing web of intertangled roots beneath my feet and probably beneath my entire house as well. I shudder to think what it's doing to the foundation.

But as with all things in nature, Japanese Knotweed does have useful purposes. According to Wikipedia again:

Japanese Knotweed flowers are valued by some beekeepers as an important source of nectar for honeybees, at a time of year when little else is flowering. Japanese Knotweed yields a monofloral honey, usually called bamboo honey by northeastern U.S. beekeepers, like a mild-flavored version of buckwheat honey (a related plant also in the Polygonaceae).

The young stems are edible as a spring vegetable, with a flavor similar to mild rhubarb. In some locations, semi-cultivating Japanese Knotweed for food has been used as a means of controlling knotweed populations that invade sensitive wetland areas and drive out the native vegetation.

Although I certainly can't allow these things to take over my garden (surprisingly, though, my basil is thriving amongst it), I think I may allow a few examples of it to remain intact for further study. There's something about it that intrigues me - something more than I've stated here - but I can't seem to put my finger on it. Will report more later.


  1. japanese knotweed (Polygonum Cuspidatum) is a cousin of one of the 22 Chinese super tonic herbs (polygonum multiflorum.) it is also the primary commercial source of resveritrol the super antioxidant known for extending life.

  2. Is it true that some parts of rhubarb is poison?

  3. Michael, no they aren't. Some parts, all parts actually, of rhubarb are TOXIC, there's a difference. If you eat a whole lot of it it will make you sick, but you'd have to eat several pounds at a sitting (uncooked) to even do that. It contains a chemical called oxalic acid, which is basically harmess except in huge quantities.

    By the way, Japanese knotweed also contains oxalic acid, so you may not want to eat several pounds of that in a sitting either, lol.