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Japanese Knotweed: A Delicious and Medicinal Invasive

At The Outdoor Apothecary homestead, we place significant emphasis on incorporating native plants into our landscape and protecting the ones we already have. However, this can be a challenging task due to the presence of invasive species that compete for limited resources and space. 

Among the invasive plants we have had to contend with is the notorious Japanese Knotweed. However, despite being known as an invasive plant species that poses a threat to native biodiversity and causes damage to infrastructure, it has several edible and medicinal properties that are often overlooked. That’s right, you can turn your problem into a delicious and healthful solution. In fact, in the Spring, one of the ways we manage this invasive is to eat it and use it to make medicine. 

This article will focus on exploring the nutritional and medicinal benefits of Japanese Knotweed and its diverse range of uses, as well as the safe handling of this plant to minimize its spread. 

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Identifying Japanese Knotweed

Maybe you’ve never heard of Japanese Knotweed, or you’re not sure if you have this pesky plant growing on your property. Don’t worry, identifying it is easy once you know what to look for. Here’s a quick guide on how to identify Japanese Knotweed:

First off, Japanese Knotweed (Fallopia japonica) can grow up to 8 feet tall and has hollow stems that are bamboo-like in appearance. The leaves are heart-shaped and alternate along the stem, and are about 6 inches long. The plant also produces small white or greenish-white flowers in late summer or early fall.

One of the most distinctive features of Japanese Knotweed is its reddish-brown, woody stems that have a zigzag pattern. These stems are also covered in small, raised bumps, which give the stem a slightly rough texture. Another identifying characteristic is the way the leaves are arranged on the stem – they appear to be growing out of the stem at a slight angle, giving the plant a ladder-like appearance.

It’s important to note that Japanese Knotweed can easily be mistaken for other plants such as bamboo, which also has hollow stems and a similar growth habit. However, bamboo leaves are long and narrow, whereas Japanese Knotweed leaves are wider and more rounded.

If you do find Japanese Knotweed on your property, it’s important to manage it carefully, as it can quickly spread and take over an area. This can be done through digging up the plant, cutting it back regularly, or using herbicides. However, it’s important to note that removing Japanese Knotweed can be a difficult and time-consuming process, so sometimes it’s best to seek professional help if you’re unsure how to proceed.

leaves & flowers
Stem
Sprouting in early April - Northeast CT

Harvesting Japanese Knotweed

Japanese Knotweed may be invasive, but it’s also a delicious and nutritious plant that can be a great addition to your diet. It is rich in a variety of vitamins, minerals, and other beneficial compounds. It is particularly high in Vitamins A and C and contains potassium, zinc, phosphorus, and manganese. Additionally, it contains a range of antioxidants, including resveratrol, which has been shown to have anti-inflammatory and anti-cancer properties. 

The best time to harvest Japanese Knotweed is in the spring, when the young shoots are tender and about 6-8 inches tall. It’s best to harvest the shoots before the leaves fully unfurl, as they can sometimes become tough and fibrous afterward (the ones pictured below are a bit more mature than I like, but I’m going for it anyway). 

Use a sharp knife to slice off the youngest and plumpest green shoots at the base. For taller and more mature shoots, slice higher up. The goal is to harvest the meristems, which are the actively growing parts of the plant and are most tender toward the tip, much like asparagus. Your knife will guide you, and you shouldn’t need to exert much effort. If the stems are tough, peel the membrane away, and discard the joints between each hollow section. However, very tender shoots can be eaten whole.

Eating Japanese Knotweed

Before preparing Japanese Knotweed, it’s important to note that the plant contains oxalic acid, which can cause kidney stones if consumed in large amounts. However, the amount of oxalic acid found is similar to that found in other foods like spinach and rhubarb, so moderate consumption is safe for most people. If you have a history of kidney stones or are at risk of developing them, it’s best to avoid eating Japanese Knotweed altogether.

But, if you are looking for a foraged meal, Japanese knotweed plants can provide several edible parts. With a taste similar to rhubarb, you can harvest the plant’s leaves, shoots, and roots to enjoy their sustenance. 

While most of the nutrients are carried by the shoots and roots, the leaves are still fit for human consumption. You can eat them raw in a salad or cook them with other vegetables, although I find that their flavor is too strong for me and they are a bit too fibrous for me to enjoy. 

The roots contain the most nutrients, including high concentrations of resveratrol. The California Department of Food and Agriculture and the book Cornucopia II both say the rhizomes are edible, however no references are given as to how to cook them, nor have I tried. Usually, I just use the roots medicinally in tinctures. 

Young shoots can be harvested from early spring to late summer, and their tough outer layers can be peeled back to reveal a tasty treat that can be eaten raw, sautéed, or fried. 

However, be careful where you forage for these plants, as consuming Japanese knotweed from areas where workers have sprayed them with herbicides can lead to serious illness. Avoid roadsides, ramps, and landfills when collecting your edible plants.

Medicinal Properties of Japanese Knotweed

Japanese knotweed has been used in traditional medicine for centuries and is still used by herbalists today, including myself. Recent studies have shown that it contains several compounds with potential health benefits. Here are some of the possible medicinal properties and uses of Japanese knotweed, along with sources to support these claims.

  1. Anti-inflammatory: Japanese knotweed contains resveratrol, a potent anti-inflammatory compound. Resveratrol has been shown to reduce inflammation in various diseases, including arthritis, cancer, and heart disease. (Source: Biomedicine & Pharmacotherapy)

  2. Antioxidant: Japanese knotweed also contains high levels of flavonoids and other antioxidants, which can protect cells from oxidative damage and reduce the risk of chronic diseases. (Source: Food Chemistry)

  3. Cardiovascular health: Resveratrol in Japanese knotweed has been found to improve heart health by reducing blood pressure, lowering cholesterol levels, and preventing blood clotting. (Source: Journal of Medicinal Food)

  4. Anti-cancer: Several compounds in Japanese knotweed, including resveratrol and emodin, have shown potential anti-cancer effects in laboratory studies. They may help prevent the growth and spread of cancer cells and induce apoptosis (programmed cell death). (Source: Molecules)

  5. Neuroprotective: Some studies suggest that resveratrol in Japanese knotweed may have neuroprotective effects and could be beneficial in the treatment of neurodegenerative diseases such as Alzheimer’s and Parkinson’s. (Source: Frontiers in Aging Neuroscience)

  6. Lyme Disease treatment: An article in Medical News Today reports that Japanese knotweed  is one of the plants whose active compounds appear to be highly effective against the bacterium that causes Lyme disease. As someone who has had Lyme several times, this is of the greatest interest to me. I take a prepared tincture preventatively throughout the warmer months. 

Note: Japanese Knotweed medicine is most often prepared by making a root tincture. 

Sources:

  • Boakye YD, et al. “Anti-inflammatory properties of Fallopia japonica, a plant species used in traditional medicine for the treatment of inflammatory disorders.” Biomedicine & Pharmacotherapy, 2018.
  • Wu X, et al. “Antioxidant activities and polyphenolic compositions of Chinese medicinal herb Fallopia multiflora.” Food Chemistry, 2011.
  • Wong RH, et al. “Physiological and therapeutic roles of resveratrol in mammals and its effect on blood platelets.” Journal of Medicinal Food, 2012.
  • Li W, et al. “Emodin: A Review of Its Pharmacology, Toxicity, and Pharmacokinetics.” Phytotherapy Research, 2019.
  • Zhang H, et al. “Resveratrol attenuates Aβ-induced neurotoxicity via the Notch signaling pathway.” Frontiers in Aging Neuroscience, 2017.

Controlling the Spread of this Invasive Plant

As I mentioned earlier, controlling the spread of this incredibly invasive plant is important because if left unchecked it WILL outcompete native vegetation, cause damage to infrastructure, and even reduce property values. There are several methods for controlling the spread of Japanese knotweed, including physical removal, chemical treatment, and non-chemical control.

  • Physical removal involves digging up the plant and its root system, which can be a time-consuming and labor-intensive process. However, it can be effective if done properly, as even small pieces of the root system can sprout into new plants if left in the soil.
  • Chemical treatment involves using herbicides to kill the plant and prevent it from regrowing. This method can be effective, but it must be done carefully and in accordance with local regulations, as the use of herbicides can have negative impacts on the environment (I am loath to recommend this method).
  • Non-chemical control, such as covering the plants with plastic or black mats, can also be effective at controlling the spread of Jthis plant. This method is often used in combination with physical removal to ensure that no sunlight can reach the plant and allow it to regrow.

When it comes to disposal, it’s important to do so properly to prevent the spread of the plant. The plant should never be composted or thrown away with other yard waste, as this can spread the plant to new locations. Instead, it should be carefully bagged and disposed of in a landfill or incinerated in a licensed facility. In some cases, local regulations may require that Japanese knotweed be disposed of as hazardous waste due to its invasive nature. It’s important to check with local authorities to determine the proper disposal methods in your area.

By taking appropriate measures to control the spread of Japanese knotweed and dispose of it properly, we can help prevent its negative impact on the environment and infrastructure.

Sources:

  • Environment Agency. “Managing Japanese knotweed on development sites.” 2018.
  • Natural Resources Wales. “Japanese Knotweed Code of Practice.” 2013.
  • Scottish Natural Heritage. “Japanese Knotweed.” 2020.
  • USDA Forest Service. “Japanese Knotweed.”

Disclaimer: outdoorapothecary.com is informational in nature and is not to be regarded as a substitute for professional medical advice and should not be relied on as health or personal advice. While we strive to be 100% accurate, it is solely up to the reader to ensure proper plant identification. 

Some wild plants are poisonous or can have serious adverse health effects. We are not health professionals, medical doctors, nor are we nutritionists. It is up to the reader to verify nutritional information and health benefits with qualified professionals for all edible plants listed in this website.  The information provided is not intended to diagnose, treat, cure or prevent any disease. Always seek the guidance of your qualified health professional with any questions you may have regarding your health or a medical condition.

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This post first appeared on The Outdoor Apothecary, please read the originial post: here

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Japanese Knotweed: A Delicious and Medicinal Invasive

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