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weed with seed pod like tomatillo

My Backyard Weeds – Ground Cherry

There is a weed that grows seed pods that look like little Chinese lanterns. It is commonly called ground cherry, but it is also known by everything from Mexican husk tomato to gooseberry. The Golden Guide titled Weeds says there are about 80 species under it’s Latin genus of Physalis, but the Handbook of Poisonous and Injurious Plants (HPIP) says only 17 of these grow in the United States. HPIP also lists 25 different common names for this weed.

The little lanterns might be cute if it weren’t for other characteristics of this weed:

The roots grow deep networks
The stem breaks easily at the root
The leaves and unripe berries are toxic

The toxicity is the same as caused by potatoes, due to solanine glycoalkaloids. The symptoms are gastrointestinal and neurological, with the severity of them depending on the dose. This University of California, Davis Review of Important Facts about Potato Glycoalkaloids succinctly covers the important details. In summary from this site and HPIP, the effects are:

  • headache
  • nausea
  • vomiting
  • diarrhea
  • abdominal pain
  • fatigue
  • hallucinations

While my chickens have safely foraged in a pen with a few ground cherries (the plants soon died from the constant scratching), I would be careful about letting animals like goats or horses around them. I am also going to be careful with disposing of them while my lab puppy is around, as she likes to chew on many things I pull from the garden. However, some people do harvest the fruits (completely ripe) and think they taste yummy.

Unlike some weeds, ground cherry is not all that bad to look at. There are some species in the genus that are grown for ornamentals and to harvest the ripe berries. Wild animals also eat them. The photo below is from the Missouri State weed page . They have an extensive library of weed photos there.

The plant’s presence above ground begins with a single stem that grows straight up for a couple of inches, topped by a tight bunch of leaves. This floret of leaves soon opens up, and not long after the plant forms branches that remind me of pepper plants. It is about the same height, too, typically being 1 – 3 feet high at maturity.

The variety of ground cherry that grows in my yard has shiny, smooth edge, eliptical shaped, deep green leaves. According to some resources, some plants have fuzzier leaves with some being more pointed and some more rounded.

As soon as the plants get to full size, they are quick to flower. The flowers are bell shaped, usually yellow with some dark spots in the center.

It doesn’t take much longer for the lantern seed pods to form, then dry, and drop all over the ground. Once they are dry, the lanterns break open quite easily, spreading seeds willy-nilly.

As I show in my video, digging the plants out can be frustrating. Not only do the stems or upper root sections break easily, but there are strong lateral roots under the ground that remain to sprout again. This Oregon State University extension drawing also shows these robust and evasive lateral roots . These roots seem to be perennial, as the plants tend to come back in the exact same spot year after year.

I have been able to successfully grow grass over a bare patch that once regularly sprouted an abundance of ground cherry. The grass is treated regularly to control broadleaf weeds. In other places, regular chicken scratching has eradicated the plants.

I have used weed killer, specifically Round-Up, on ground cherry in my vegetable and flower beds with limited results. It seems to knock the plant back mildly, but it keeps growing and rejuvenates quickly. It is hard to cut it back regularly enough to deplete the vitality of the roots, but if you have a small garden and a small patch, that helps some. As this summary of eradication strategies discusses , even the ornamental ground cherry varieties are considered highly invasive.

Basically, this is not a weed that you want to let grow at all. It is not just a matter of pulling up the plants at your convenience. Once it gets a foothold, there will an ongoing battle.

Horse nettle Beware the Wild Perennial Tomato

Q. We bought our first house two years ago. Lots of old trees and space to garden, but also horse nettle, which looks like potato or eggplant, but has spikes from the tips of the leaves all the way down to the soil. It spreads like crazy, and while pulling it out makes it go away for a little while (and makes me feel good), I’m only holding the line, not winning the fight. I found some advice at the Penn State University Extension website, but I can’t find anything closer to home. What’s the best way for me to control this tenacious weed? I’m more than willing to try a flame weeder, cut the little seedlings down, and/or keep pulling. Thanks so much for your advice!

—-Maizie in Lewes, Delaware

A. Yes; the common name of this plant is “horse nettle”, but it looks like a spiny eggplant when young and a yellow cherry tomato when mature—which makes sense as it’s in the tomato/potato/eggplant family. The flowers look like eggplants; the leaves smell like potatoes when you crush them; and the fruits look like little yellow tomatoes—but they’re poisonous. It also has the nasty spines she mentioned; hence the botanically incorrect but helpfully informative common name that includes the warning word ‘nettle’. And it’s perennial; in fact, its underground rhizomes are said to be as tenacious as running bamboo.

So: where did this alien invasive monster come from?

The Carolinas. It’s native to the American South and one of a surprising number of poisonous plants in the tomato family found in the US, including Jimsonweed (aka Angel’s Trumpet, which is what you’ll hear if you eat any part of it); black henbane, which has gorgeous flowers but can be fatal to farm animals when its growing in fields cut for hay; and the deadly nightshade sisters—bittersweet and black.

But the same family also includes peppers, tobacco and the famed Nicandra, or “Apple of Peru”—a tomato-like plant that has a long folk history of repelling flies. Nicandra isn’t poisonous, but it is considered an invasive weed—although many farmers swear by its ability to keep flies away. Or maybe just kill them. Nobody knows for sure.

So what does our listener need to do about her weird weed?

Rule Number One: Don’t plant any yellow cherry tomatoes nearby if you’re easily confused!

Seriously, the bitter taste would make you spit this fruit out instantly if you did try one. Now, all of the literature on this plant agrees that herbicides are useless. And cultivation, especially with a tiller, would make the problem much worse as it would cut up and then replant thousands of the rhizomes. (That’s how they deliberately plant horseradish. They just till the field after harvest and all the little root bits they missed get chopped up and replanted for the following season.)

All of which means that it’s time for my ‘rope a dope’ tough-weed technique.

In Year One, cut down the plants as soon as you can ID them. Force the roots to expend energy growing new leaves but try not to allow any of those leaves to reach the size where they can achieve photosynthesis. You’ll eventually starve the plant, which is used to being left alone to spread via its rhizomes and by dropped seed. (You could use a weed whacker to keep up with the job; but only if you make sure to always wear good shoes, long pants and such. You want to keep the toxic juice and nasty spines offa your bare skin.)

In Year Two I would continue to cut the plants back until we get to a hot dry stretch in the summer, and then use a flame weeder to toast newly emerging baby plants; or spray them with a non-toxic herbicide like herbicidal soap or one of the newer iron-based broadleaf herbicides. But you have to knock the plants down for a full season first so that the new sprouts will emerge small and weak enough to be vulnerable to these tactics..

Another alternative is to solarize the soil. Keep cutting them back now. Then scalp the area super low in the spring, really saturate it with water and cover it tightly with one or two mil thick clear plastic, as we describe in the soil solarization article in the A to Z Gardens Answers section of our website. It’ll take a full growing season in Delaware, but the underground rhizomes will be really most sincerely dead by Fall if you follow the directions carefully.

And finally: is a Delaware gardener correct to try and find advice that’s more local than PA’s Extension service?

No. Her conditions are essentially the same as in PA; heck—you can step into Delaware from parts of PA. What you don’t want to do is take advice from a state that has wildly different growing conditions—like California or the Dakotas.