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In The Grow Question and Answer - Gardeners worn down; clearweed may be culprit

November 6, 2018
Closeup of what is likely clearweed

Q: I have had a garden on our property for about 14 years. Naturally, we’ve always had to deal with weeds, but until last year they had been the usual crabgrass and other types that could be controlled if you kept ahead of them.

But last year, some type of weed or ground cover has sprung up, and it’s infuriating!! There is absolutely no way to weed it out by hand because it comes up almost like a ground cover. Last year I gave up on the garden because I work full time and just couldn’t keep up with it. This year, my husband took to tilling and retilling the open areas in the garden to try and prevent it from overtaking everything again. I’ve attached a few pictures to show you what it looks like close up and all over the garden (or what’s left of it!). Can you tell us what this is and what we can do to control or prevent it next year? – J.P., Bartholomew County

A: I love your photos, especially the one with the pink flamingo!

I believe this is a plant called clearweed, Pilea pumila in the nettle family and native to most of the eastern two-thirds of North America. It is an annual (lives for only one growing season) but is a prolific seed producer. The seeds are tiny and spread by wind, so they show up in lots of places where they might not have been previously. Repeated hand pulling, tilling and mowing will help reduce seed formation to reduce future populations, but there is likely plenty of seed bank still in the soil from previous years. Mulching may help reduce future populations from sprouting. Or perhaps consider planting with permanent ground cover or temporary cover crop.

Here’s some additional information on this plant.

http://www.illinoiswildflowers.info/woodland/plants/clearweed.htm

https://plants.usda.gov/core/profile?symbol=pipu2

Q: I’m sending photos of a plant am concerned about. Several of these plants have appeared this year under the bird feeder tray. I’m afraid it might be an invasive species that came from some of the birdseeds. It resembles lopseed that grows nearby. However, it appears more robust, having thicker joints. The leaves are smooth and not toothed. I can’t find anything that is quite like it in my plant identification books. Should I dig them up? ­– M.L.

A: I think your plant is indeed American lopseed, known botanically as Phryma leptostachya. This species is an herbaceous perennial native to most of North America, though not all that frequently seen. The size and robustness of plants can vary considerably depending on environmental conditions. Since these specimens are growing under the bird feeder, they may be getting “fertilized” by the visiting birds! You’ll find additional info on lopseed at the following links.

http://www.illinoiswildflowers.info/woodland/plants/lopseed.htm

https://plants.usda.gov/core/profile?symbol=phle5

https://michiganflora.net/species.aspx?id=1914

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