Water Hemlock: Wildflower Wednesday

– Posted in: Native/Invasive

A couple of weeks ago, my thirty-something daughter was busy gathering wildflowers for her brother’s wedding. “Mom, do you know what that plant is?” There it was, growing in our backyard along the creek. I am pretty sure it has been there ever since we moved in almost five years ago. But no, I didn’t know what it was. “Well, it looks a lot like wild parsnip, except the flowers are white instead of yellow. I think I’ll leave it alone.” (You can read more about wild parsnip here.)

Of course, after that I had to figure out what it was. And the answer surprised me. Who would have guessed that “the most poisonous plant in the North Temperate Zone” (per ethnobotanist H. D. Harrington, as quoted in a USDA Forest Service article) was growing right there in our backyard? Allow me to introduce you to water hemlock, more formally known as Cicuta maculata.

water hemlock full plant

At 4 to 5 feet tall, water hemlock is an architectural plant. If it weren’t so poisonous, we’d say it adds structure and texture to an arrangement.

water hemlock flower

The flowers are reminiscent of Queen Anne’s lace, another plant in the same family.

water hemlock leaves

The lacy leaves are thrice pinnately compound, according to the USDA Forest Service. Illinois Wildflowers says the compound leaves are odd-pinnate or doubly odd-pinnate. Minnesota Wildflowers just says double compound leaves. I love it when there’s a picture so I don’t have to decipher the specialized vocabulary.

water hemlock leaflet close-up

The veins in water hemlock leaflets end in the notches of each lobe, instead of the tips. This is one of the clinchers in identification.

What good is it?

By now you are wondering if I yanked it all out of the ground right after I took the pictures. No, I didn’t. Number one, I didn’t want to inadvertently get juice from this plant on my hands. Sure, I could wear gloves, but then I’d have to throw out the gloves. And what’s the proper way to dispose of the pulled plants? Two, my kids still living at home are old enough to leave a plant called “suicide root” by Native Americans strictly alone, and we don’t have any animals that would eat it. Three, lots of living creatures find this plant useful.

bug eat fly on water hemlock

I think the fly is getting eaten by the…uh–something.

According to the Illinois Wildflower website, larvae of the black swallowtail butterfly feed on the leaves of water hemlock, and more than a dozen genera of insects feed on the nectar. I suspect many of these insects help pollinate our vegetable garden nearby. And why needlessly disturb a functioning native habitat when there are plenty of invasive plants I could be removing?

Truly, I haven’t made up my mind. If I do decide to remove it, I want to think about the smartest, least harmful way to go about it. And if I do decide to eradicate it, I expect to be fighting the battle for several years, because I am sure there is a lot of seed in the ground waiting to sprout, and perhaps plants upstream ready to float more seed to our banks. There are a lot of things to consider and I don’t want to make a hasty decision. In the meantime, I’m enjoying the structure and texture this plant adds to the creek bank.

Posted for Wildflower Wednesday, created by Gail of Clay and Limestone, to share wildflowers/native plants no matter where you garden in the blogosphere. “It doesn’t matter if we sometimes show the same plants. How they grow and thrive in your garden is what matters most. It’s always the fourth Wednesday of the month!”

About the Author

Kathy Purdy is a colchicum evangelist, converting unsuspecting gardeners into colchicophiles. She would be delighted to speak to your group about colchicums or other gardening topics. Kathy’s been writing since 4th grade, gardening since high school, and blogging since 2002.

What differentiates a bulb from a perennial plant is that the nourishment for the flower is stored within the bulb itself.…There is something miraculous about the way that a little grenade of dried up tissue can explode into a complete flower.

~Monty Don in The Complete Gardener pp. 142

Comments on this entry are closed.

Nadezda August 9, 2016, 9:24 am

I know very well this plant – cicuta, and it’s very poisonous, you’re right Kathy. Here in northern area of Russia, near Saint Petersburg we have a lot of it in fields, as another one ?eracleum. Fortunately I’ve never had it in my garden.
Have a nice week!

Matt August 7, 2016, 8:09 pm

I work out in the field every day for the last 20 years and I have never heard of it! It looks very familiar probably because I have seen Queens Anne Lace and it resembles it. Thanks you for bringing this to my attention, I will definitely be on the look out now.

Stephanie August 7, 2016, 4:39 pm

Lots of common plants are poisonous (looking at you, aconitum). I say, your time and energy are better spent fighting nasty invasives–or even better, contemplating the garden with glass in hand 🙂

Rose August 4, 2016, 6:57 am

I’ve been looking at a similar weed/wildflower in back of our farm and wondering if it was wild parsnip or hemlock. Thanks for the excellent info and great photos, Kathy! I’ll have to look at mine more closely now.

Kathy Purdy August 4, 2016, 1:55 pm

Perhaps this website will help you confirm the i.d.: http://www.ravensroots.com/blog/2015/6/26/poison-hemlock-id

Lynn Gillespie August 2, 2016, 12:32 pm

What an interesting conundrum. Is there a possibility of smothering the plant to eradicate it? Then planting on top with something new? Wishing you the best of luck in whatever you do with the plant!

Pat Webster pat@siteandinsight.com August 2, 2016, 8:01 am

What a shame that water hemlock has poisonous qualities. Like giant hogweed, it is such an attractive plant. Many will disagree, but I’d simply leave it where it is. If you don’t touch it, it won’t bother you.

Lea August 1, 2016, 3:34 pm

Good photos, and interesting information
Have a great week!

Barbara Bell July 28, 2016, 8:50 am

Is this also related to Giant Hogweed? I know it’s extremely poisonous too, and resembles Queen Anne’s Lace on steroids. I had always read that it was the most dangerous wildflower.

Kathy Purdy July 28, 2016, 7:40 pm

Giant hogweed and water hemlock are in the same family (Apiaceae). As best I can determine from a quick Google perusal, giant hogweed is phototoxic, just like wild parsnip is. They both have sap that burns the skin chemically when exposed to sunlight. (And wild parsnip is a lot more common around here.) I don’t think water hemlock irritates the skin. It is deadly when ingested, and the reason you would avoid touching it is so that you don’t inadvertently transfer the sap to your mouth. As far as which is the most dangerous overall, I wouldn’t know. But my quote said water hemlock was the most deadly plant native to the North Temperate zone. Giant hogweed is native to the Caucasus–would that be considered North Temperate?

Kathy Sturr July 28, 2016, 6:38 am

Never knew! Thank you for, once again, teaching me about a new plant. I will now know this plant if I run into at the lake! If I were you, I would contact my local extension and ask their opinion.

Corner Garden Sue July 27, 2016, 10:07 pm

What a beautiful plant! I didn’t know what it was. I have heard of water hemlock, but didn’t know what it was. That may be an ambush bug eating the fly.

Becky July 27, 2016, 8:56 pm

Did you notice the fragrance of the flowers? Dead mouse? I haven’t seen it anywhere but in the poisonous plants garden at Cornell!

Kathy Purdy July 27, 2016, 8:59 pm

Actually I didn’t think to smell it . . .

gail eichelberger July 27, 2016, 6:15 pm

The leaves are actually quite interesting and would add something special to a garden~Were it not so poisonous!

Leslie July 27, 2016, 5:50 pm

Your daughter was smart to ask before picking although I am sure it is you who taught her well.