This is about the time of year we begin to see some rather alarming posts on social media that sound like we are being invaded and attacked by a poisonous plant. They usually get a lot of shares which is oftentimes more to the point of the post rather that the sharing of an actual threat. The topic of these posts is poison hemlock. Yes, poison hemlock can be found in the wild, along streams and ditches. So let’s talk about poison hemlock.

This is the time of year we start to see Queen Anne’s Lace popping up along the roadside etc. Queen Anne’s lace is the wild ancestor of the domesticated carrot. It does produce an edible root like the carrot we are used to, but it’s not very tasty. One of the challenges is that Queen Anne’s Lace looks very similar to poison hemlock to the untrained eye.

From a distance, they are challenging to identify because they both produce small white flowers and similar growth. To make a positive identification, you’re going to need to look at the stem of the plant. The stem of poison hemlock has distinctive purple spots. In contrast, Queen Anne’s Lace does not have these purple splotches but has a hairy stem. Cow parsnip (a cousin) has a ribbed stem. Neither of these contain the poison found in poison hemlock. Poison hemlock also has a distinctive smell in the summer. For lack of a better description, it smells like cat urine.

Where the plants are growing is also an indicator of its identity. Poison Hemlock can be found growing in shady, moist places. Oftentimes it will be located along streams or ditches. However, from there, it can spread to other nearby areas.

One thing that separates these plants is the name “poison” and it’s not just a nickname. Most of the toxins found in the plant are in the seeds, roots, and lower stems. Don’t eat this plant. Doing so can cause respiratory paralysis, coma, and potentially death. I’m guessing most of us wouldn’t just yank up a plant we found growing in the woods and begin to snack on it, but you never know.

The primary threat from Poison Hemlock is to wildlife and livestock. Pigs are most at risk, but it is also dangerous for goats, sheep, horses, and cattle to ingest. Unfortunately, poison hemlock can sometimes be found in contaminated hay. If you identify this plant in areas where you have grazing animals, you should try to eliminate it.

To begin your path toward elimination of this plant, begin by mowing it. This will stress the plant and inhibit its ability to uptake nutrients. Then herbicides such as 2,4-D or dicamba can be used to finish them off. Just remember, you’ll likely have to repeat this process every year for between 3 and 6 years because its seeds can remain viable in the soil for up several years.

As you engage with getting rid of the poison hemlock, it’s a good idea to wear protective clothing and a mask because even touching this plant can cause a rash in some people. So, remember, purple on the stem, stay away from them. Good luck.

You can get answers to all your gardening questions by calling the Tulsa Master Gardeners Help Line at 918-746-3701, dropping by our Diagnostic Center at 4116 E. 15th Street, or by emailing us at mg@tulsamastergardeners.org. Photo: Jeff Stachler, The Ohio State University, Bugwood.org