Turkey Red Journal
Beware the Interloper!
John Marshall
For several years running I had either never seen, or was simply unaware of, an interloper in my indigo garden. I grow Japanese indigo, tadeai. It does amazingly well in my garden in Northern California. A few years ago I noticed what I thought to be simply one more variation, of the several versions, of this dye plant. It has long, spindly leaves and a dark spot in the middle of each. What caught my eye was not the leaf shape but the fact that it always bloomed earlier than any of its sisters. I checked with friends in Japan, and they assured me that it is tadeai, but not used for dyeing. By tadeai, I assumed they meant Persicaria tinctoria. It turns out it is Persicaria, just not tinctoria.
| Persecaria tinctoria in September | Persecaria maculosa in June |
| P. tinctoria, shown here on the left, blooms much later in my garden than the P. maculosa, shown on the right. The photo of the P. tictoria was taken in mid-September, and the P. maculosa was shot in early June. | |
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| Photograph Copyright by John Marshall | Photograph Copyright by John Marshall |
Since they were so easy to spot, I harvested all I could find that year and tried several tests: First, the simple rub test (taking a leaf and rubbing it against piece of white silk). I got no more than grass stains from the suspected interloper.
Next, I tried drying the leaves. The leaves I've been using for dyeing dried to a rich, deep aqua. The interloper dried to a pale green. And, before giving up, I tried fermenting each to see if I could realize any pigment from the uninvited guest, and this test, too, came up negative. (It does, however, give nice yellows with a mordant.)
OK, that was enough evidence to tell me that I don t want this plant in my garden. Since that time I have ruthlessly banned it from my presence, and having developed this passion to purge, I have started noticing it across a wide territory, far from my home.
As it happens–and what prompted this article–Dustin Kahn (a board member of Fibershed) contacted me about a problem an individual was having with her garden bed. She purchased seeds through me, but what came up in all its bold-faced audacity was only the long-leafed fiend. Kori Hargreaves, a plant biologist, identified the crop as P. maculosa, not P. tinctoria. And just as this correspondence was going on, John Brittnacher, biologist and part of the indigo study referenced elsewhere in this edition of the TRJ, wrote to me telling me that this same knotweed had appeared amongst his chosen and was promptly invited to leave. I wondered if there might not be some cross-pollination going on, but the P. maculosa blooms so much earlier that the chances of that happening seem slim. Kori proposed that perhaps the seeds may have been introduced from outside if the soil was amended, and that could account for their abundance. We still don't really know what happened in that garden mentioned earlier, but this would seem to be a problem that we, as a community, haven't discussed much.
Democrat, Republican, Green Party, or Independent, do not suffer this common foe to propagate amongst the innocent.
| Persecaria maculosa | Persecaria tinctoria |
| Perhaps a side-by-side illustration will help you to pick out the differences. Both shots were taken in my garden on August 1, 2018. P. maculosa on the left, and P. tinctoria on the right. | |
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| Photograph Copyright by John Marshall | Photograph Copyright by John Marshall |
To recap: The interloper has long narrow leaves and there is a much darker spot in the center of the leaf. The general growth structure is similar between the two plants since they are both Persicaria, but P. maculosa tends to branch more than unmolested P. tinctorium and is more spindly. In my garden, it begins blooming as early as mid-July, whereas the sanctioned tadeai never blooms here before mid-August.
Action: When spotted, promptly remove and destroy.
Caution: Even within P. tinctoria, the tadeai you want growing in your garden, there are many variations in stem and leaf structure. Some have nearly round leaves, some red stems. Some bloom pink, some bloom white. Many of the indigo-producing plants do have long and slender leaves, and if you look really hard, in dazzling sunlight, you'll start to see what may appear to be a darkish spot in the middle of the leaves.
And while I'm on my soapbox, this is just a reminder: P. tinctoria seeds are only reliably viable for one year. Never hold them over thinking you'll get them in the ground next season. When making bread I always start my yeast in a separate bowl and make sure it is robust before adding it to the other ingredients. With the same concept in mind, it is always a good idea to start your seeds in a shallow tray and transplant them once you see they are doing well.
Otherwise, enjoy spreading your seed among those longing for the Gospel of the Blue!