I first encountered Japanese knotweed (Polygonum cuspidatum) on a 400-acre botanical sanctuary in southeast Ohio where I was completing an intensive internship in the conservation of native medicinal plants. As the sanctuary was a refuge for threatened Appalachian medicinal plants, like goldenseal and ginseng, the sanctuary did not use any kind of herbicides on unwanted plants. Unlike the other “invasive” plants found on the sanctuary—tree-of-heaven, multiflora rose, Japanese honeysuckle, Russian olive—Japanese knotweed was not a target of our manual work efforts. Indeed, manual control of Japanese knotweed was considered a nonstarter: every small root fragment can re-sprout and effective removal would have required sieving the soil of the entire area of infestation. 

Once I learned to recognized Japanese knotweed, I began to see it many places, and when I moved to western Oregon a decade ago, that pretty, but intractably aggressive plant, was there ahead of me. I spotted Japanese knotweed growing in our yard in Eugene, in wet roadside ditches, in riparian areas up to the Cascades and out to the Pacific coast. Our neighbor cut and sprayed the knotweed, but year after year it came back, perhaps more vigorously than before. Before long, the plants had spread outside our fence and appeared in patches in a nearby field. Non-native plants that spread aggressively are what ecologists and land managers call “invasives”. 

By the time I saw knotweed spreading in my own neighborhood, I was employed as a post-wildfire restoration ecologist in the McKenzie River Valley east of Eugene, identifying and mapping “invasives” for what is called “treatment.” Japanese knotweed was “number one on our hit list. Our “best management practices” dictated that Japanese knotweed receive a foliar spray of glyphosate or imazapyr, two chemical herbicides, just after flowering in early fall, before the leaves senesced. And this, for multiple years. The effectiveness of these chemical treatments is questionable; landowners who had sprayed the plants for multiple years still had dense stands of knotweed creeping along their creek edges. At one such site, a mid-summer scrape of bare earth was broken by the sad, reddened stems of knotweed, tenaciously pushing up through the ground. The plants were stressed, but still very much alive. The use of the herbicides—by those who would restore and protect the land—depressed me, and I wanted to think about ways to engage this plant that was so vigorous, so beloved by late season insects, and thriving in the toughest neighborhoods, both urban and rural. 

Although I knew Japanese knotweed was considered edible and that herbalists were using the plant to treat Lyme disease, it wasn’t until I began studying local plants as natural dyes that I gathered and used the plant myself. Japanese knotweed is a member of the same genus as Japanese indigo (Polygonum tinctorium syn. Persicaria tinctoria, also called “dyer’s knotweed”), a plant cherished as as long-lasting blue dye. I first tried using knotweed leaves as I might use those of indigo and obtained a light, not very interesting tan color, but a friend who had begun using knotweed stems and leaves for papermaking told me to try the roots for dye. I dug a few from the yard in Eugene and got a rich, gold hue. 

When I moved to Moscow, Idaho in the summer of 2022 to begin work towards a doctoral degree, I wasn’t sure who I would encounter botanically. The Palouse region differs greatly from the landscapes of Western Oregon: the vistas are filled with rolling hills of loess or wind-deposited soils. Once tallgrass prairies, these hills are now industrially cultivated for wheat, lentils and chickpeas. But in the wooded draws and ridgetops, many of the same or closely related woody species are growing. And on my first visit to see Ronnie H, an octogenarian whose family has lived on the same Palouse land west of Colfax for over a hundred years, I noted many familiar plants. His farm, a mix of remnant prairie, riparian areas thick with dogwood and hawthorn, agricultural fields and gardens surrounding an old farmhouse supports a great variety of plants, both native and non, useful as dyes and medicines. Seeing a small but healthy patch of Japanese knotweed close to the house, I offered to come out one day and dig some to use for dye. In October 2023, with the help of fellow student Lauren O, Team Naughtweed was formed, and we arranged to go out to Ronnie’s and begin digging. 

Ronnie had watered the knotweed for several days prior to our visit, and the three of us were able to dig out the whole patch within a couple of hours. But one of the reasons Japanese knotweed is so tenacious is the structure of its root system: like an underground rebar it plunges deep taproots vertically into the soil and sends out a proliferation of horizontal stolons just below the soil’s surface. As we dug and pulled, the deep tap roots broke off at 10 to 12 inches of depth; it is almost certain that the patch is back this spring. 

To use the plants for dye, I sprayed and scrubbed the roots—technically rhizomes or rootstocks—multiple times with water. Then I cut off all the aerial parts and the roots that were rotting, and these went to Ronnie’s burn pile—fingers crossed they don’t sprout there! At home, I cut down the smaller roots and scraped off the inner bark from larger, woody roots with a knife, prioritizing the parts that showed a deep orange color. After two days of processing, I had more than three pounds of fresh plant material. For the dye process, I followed a traditional Japanese method developed by Akira Yamazaki as reported in Dominque Cardon’s encyclopedic reference, Natural Dyes: Sources, Tradition, Technology and Science. I placed the roots and root bark in water overnight, then brought them to a boil for an hour, poured off the colored liquid, and added fresh water. I did this seven times, combining baths 1-4 and 5-7. After 7 extractions, the roots still appeared to have a lot of color in them, so I let them sit in water for an additional five days, and then made one final extraction which I kept separately. The extractions were allowed to oxidize for a few days before the final dye process. For this, I combined the first seven extractions, added the fibers to be dyed, and brought the bath slowly to a boil. I allowed the bath to cool, removed the fibers to apply an alum mordant, and then returned them to the boiling dye bath for a second time. 

This method yielded a deep gold similar to my first trial with Japanese knotweed back in Eugene. Having noticed that the multiple, subsequent extractions shifted in both pH and hue, I continued to experiment with the different extraction baths and combinations thereof. The continued experimentation led to a beautiful and surprising variety of color! I obtained colors varying from from yellow-golds to pinks and reddish-browns. The final extraction took differently to cellulose fibers (cotton and linen) than to protein fibers (silk), yielding pink on one and coral on the other. The initial extractions shifted to pinker tones when their pH was increased with soda ash, and the addition of iron acetate as a post-mordant created a dark brownish grey. Simultaneous to my experiments with color, I used traditional Japanese “shibori” resist techniques to create patterns on the cloth. 

Sasha Michelle White, shibori techniques on cotton, linen and silk using the roots of Japanese knotweed, 2023

In her essay, A Tree By Any Other Name, philosopher Karen Houle argues that while questions of ecological and social justice are normatively considered as distributive justice—who gets how much of what, whether benefit or detriment—linguistic justice equally or perhaps more powerfully impacts how humans understand, relate to, and shape the world, including questions of “rightness and wrongness—and hence culpability” (158). Houle builds her arguments by connecting J. L. Austin’s writings on language as a “performative” tool with Heidegger’s concept of “destining”: when an apple is described as a “choking hazard” or a tree as a “carrier”, the name destines them to be such. As Houle writes: 

“Only one aspect of an apple, or a Douglas fir, is reached for with one kind of word, and that quality of the thing—its color or its species’ name, or what it means for national security—emerges in response to that mode of address. It is ordered and ‘stands forth’ each time we speak, and in a certain way… What if our words for a thing…are wholly scientistic: mercury, cadmium, poisoning, samples, sample size, bioaccumulation, contamination. That world, and our relationships in that world with those special collections of entities—spruce trees and fish and clouds and lakes and babies—will more and more be revealed as chemicals, vessels, numbers, polluted.” (165-166) 

Rather than a neutral medium of communication and description, language is a system of ethics and justice. Especially within language that is “scientistic”, values and biases are naturalized within the words. These hidden, naturalized values have consequences. Not only does the scientistic labeling of “bad” plants as “invasives” deny “invasiveness” as an important botanical life strategy, dismissing the potentially beneficial roles that aggressive and quick-growing plants can have in compromised ecosystems, it also lends a veil of objectivity to what is, in fact, a value judgment. It targets plants as enemies. It unleashes connotations of war and xenophobia. It performs this “reality” and elicits that reality’s only answer: eradicate the plant by any means possible. 

Modern herbicides and pesticides were originally developed as World War 2 weaponry. Now, the rhetoric of “invasive” as ecological enemy provides the chemical industry with a morally-justified means of continuing to profit from dumping poisons into the environment in the name of the so-called “public good”. Glyphosate, one of the primary chemicals used against Japanese knotweed, is known to be carcinogenic and long-lived. Glyphosate’s residues have been detected in the fruits of non-target plants at rates higher than allowable for the marketplace even one year after application; they have also been detected in the roots of non-target plants as long as twelve years after application. Less understood are the effects glyphosate has on soils, plants, and animals–including humans–as it accumulates, transforms, and combines with other chemicals in the environment. 

Engaging Japanese knotweed as something other than an enemy led me to complex, beautiful, and useful results. Hand digging the plant and using its roots as a dye avoided the toxicities of both chemical herbicides and chemical dyes. Using a traditional dye process from its country of origin gave me a deeper understanding of the plant and of the color it produces. If language mediates and performs our relationships with the world—does our use of the word “invasive” increase or limit our understanding of Japanese knotweed? Could we use words that allow more complex understandings of and relationships with the plant “stand forth”? Could use of these words foster a more nuanced ecological and social sense of rightness, wrongness, and culpability? Could we use words that allow us to engage ethically with a naughty plant?

Note: This essay was originally prepared as part of Dr. Aleta Quinn’s Environmental Philosophy course at the University of Idaho.

Sasha Michelle White, the roots of Japanese knotweed on swatches of cotton, linen and silk, 2023

RESOURCES
Botten, N, LJ Wood, JR Werner. “Glyphosate remains in forest plant tissues for a decade or more.” Forest Ecology and Management, 493, 2021. https://doi.org/10.1016/j.foreco.2021.119259
Cardon, Dominique. Natural Dyes: Sources, Traditions, Technology and Science. Archetype Publications, 2007.
Douglas, Heather. “The Irreducible Complexity of Objectivity.” Synthese 138(3), 2004, pp. 453–473.
Houle, Karen L. F. “A Tree by Any Other Name.” The Language of Plants: Science, Philosophy, Literature, edited by Monica Gagliano, John C. Ryan and Patricia Vieira, University of Minnesota Press, 2017, pp. 155-172.
Kenner, Robert. Merchants of Doubt. Produced by Melissa Robledo and Robert Kenner. Sony Pictures Classics, 2014.