Burdock, motherwort, and nettle jungle (or It’s not always about DSV)

by Sandy Garland

Tuesday again and another chance to work in the Old Woodlot! I was rather disorganized this week as it sort of looked like rain, except when the sun came out, and volunteers arrived one at a time, so it was hard to know how big a job to tackle. So we loaded a little bit of everything into the wagon and set off for the woods.

Riddell's Goldenrod (Solidago riddellii) protected by a wire fence until they become established.

Riddell’s Goldenrod protected by a wire fence until they become established.

Kate wanted to plant something, so I gave her five goldenrods – Solidago riddellii, a species new to me. I acquired these plants this week in a trade with Renée De Vry, who manages the Meditation Garden next to the Unitarian Church on Cleary Avenue. Well worth the visit, by the way, as Renée does a fantastic job and has created a bee sanctuary as well as a truly beautiful garden filled with layer upon layer of both “tame” and wildflowers, shrubs, trees, and grasses. Stroll the paths or sit on one of the benches and just breathe in the greenness.

Ted continued to uncover and mark small trees that we’ve planted over the last few years to give them room and light to grow. We found a more suitable flagging tape for this purpose, so you’ll see little flashes of red all over the woods this week.

Jesse chose to cut burdock, which has now reached the size of small trees. After ensuring that he could identify the right plants, he set off into the east part of the woods with our heavy-duty loppers and disappeared for the next hour. Just as we were thinking about sending a search party, he appeared to ask what to do with the cut burdock, which was now filling the east trail! (For more about burdock, please see our invasive species fact sheet in English or French.)

This was Derek’s first time working in the woods. (Previously, he had helped pot up plants for the sale in early June.) We introduced him to the scythe and turned him loose in the part of the woodlot we call the pine forest – a stand of about 15 White Pine trees planted by Fisher highschool students in 1995. Derek took to scything like a pro, and quickly cut all the dog-strangling vine (DSV) in this area.

Derek scything DSV in our “pine woods.”

Derek scything DSV in our “pine woods.”

Well-rotted DSV (right) used to cover tiny DSV seedlings (left)

Well-rotted DSV (right) used to cover tiny DSV seedlings (left)

Meanwhile, I decided to finally empty the garbage bags that have been sitting next to the pine trees since last fall when a group of Carleton students filled them with DSV that they had pulled up. I wanted to use the contents to mulch around more Red Osier Dogwood shrubs where DSV seedlings were growing thickly.

Another aside: Last week, I mentioned that we were going to try to find out whether DSV plants lying on the ground would affect the growth of “good” plants near by. Naomi Cappuccino (a professor at Carleton who has been studying DSV for many years) wrote: “There have been papers on the allelopathic effects of DSV, with chemicals exuding from the roots that can harm other plants. I would be surprised if a rotting pile of DSV had the same effect though. I would imagine that the compounds in the leaves would not be stable for long in the environment, and since rotting plants, unlike living roots, wouldn’t be continually producing these compounds, I doubt there would be a problem. But you never know! I think that if you haven’t noticed anything obvious, if there is an effect it is probably small.” Which I interpret to mean: go ahead and leave the pulled DSV in the woods, but keep an eye on adjacent plants. I also Googled DSV allelopathy and found an excellent article on the ecology of DSV.

I inadvertently disturbed a bumblebee nest in this bag of dead DSV

I inadvertently disturbed a bumblebee nest in this bag of dead DSV

Unfortunately, in my enthusiasm to empty those bags, I accidentally evicted a queen bumblebee who I believe had made a nest inside. I backed away immediately and watched as she tried to figure out what had happened to her home. We moved to another part of the woods in hopes that the queen would be able to find her nest and continue to use it.

Kate and I decided to tackle an area where I have been planting Sugar Maple trees in hopes of making space for more. In addition to burdock, Motherwort, which seemed so innocuous in the spring, has now grown to be 2 metres tall, completely covering any trees and plants. We also have to watch for stinging nettles, as grabbing one in error can result in a painful sensation that lasts for hours.

Slender Stinging Nettle

Slender Stinging Nettle

Slender Stinging Nettle (Urtica dioica ssp. gracilis) is a native species and the larval host for Red Admiral butterflies. So we don’t want to remove it even though it can give our volunteers a nasty burning sensation if they so much as brush against it.

A month ago, we noticed Red Admiral butterflies paying attention to these plants and a couple of weeks later found lots of caterpillars eating and “nesting” in the leaves. We’re eagerly awaiting another generation of butterflies…

After showing nettles to everyone in the crew and pointing out potential anitdotes to the skin reaction they cause – mainly the multitude of Spotted Touch-me-nots growing nearby – Kate and I got into a discussion about what causes the skin reaction: sharp hairs covering the leaves or chemicals that the plant produces.

It turns out we were both right. The leaves and stems are covered with tiny hairs “whose tips come off when touched, transforming the hair into a needle that will inject several chemicals: acetylcholine, histamine, 5-HT (serotonin), moroidin, leukotrienes, and possibly formic acid. This mixture of chemical compounds causes a painful sting or paresthesia from which the species derives one of its common names, stinging nettle, as well as the colloquial names burn nettle, burn weed, and burn hazel” (see Wikipedia for references and more info). See also the US Forest Service database for everything there is to know about this species and its close relatives. And see WebMD for reputed medicinal uses, side effects, etc.

Summer Azure

Summer Azure

Despite the gloomy damp day, we saw a White Admiral butterfly as well as the ruffled bumblebee. The day before, I had also found a Summer Azure, a pretty little blue butterfly examining, of all things, dog poop. Although we definitely want dog walkers to stoop and scoop, it is well known that butterflies are attracted to the nutrients in dog feces. I will leave that bit of information with you to do as you wish; but please do not experiment with feces at the FWG!

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2 thoughts on “Burdock, motherwort, and nettle jungle (or It’s not always about DSV)

  1. Nice article Sandy. I enjoyed it. I have lots of stinging nettle trying to move into my yard, so will have to rethink my strategy now.

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