White Snakeroot


When I was bird watching with a group at Tifft Nature Preserve, I photographed a wooded area with a forest floor filled with flowers.

Forest floor filled with White Snakeroot.

Forest floor filled with White Snakeroot.

By showing it and not adding a caption to what the flowers were…

I got asked about a plant I pictured in the post, BOS Field Trip – Yielding Monarchs. It covers a large dark, moist area in the woods of Tifft Nature Preserve.

I called Tifft experts to make sure I was correct on identifying this plant. Two gentlemen told me it is White Snakeroot, Ageratina altissima. It is a fascinating plant with an interesting history behind it. A woman working there told me the interesting story about the plant.


White Snakeroot is a poisonous plant found in woods and thickets, growing in rich, moist soil. It spreads by rhizomes and seed and covers shaded woodland floors. It blooms late summer and grows to a height between 18″ to 48″.

The distribution is widespread according to the USDA. For information from the map go to Plants – USDA.  There is also a Lesser Snakeroot, Ageratina aromatica L. that looks very similar to White Snakeroot.


Black Snakeroot, Actaea ramosa ‘Hillside Black Beauty’ can be purchased for the garden. Cimicifuga racemosa is another taxonomic designation of what is commonly called Black Cohosh, or Black Snakeroot. Called by either name, they grow very tall in the garden. If you want all the trivia, like medicinal uses, taxonomic uncertainty, etc. about the garden varieties, go here.


Containing the toxin, tremetol, White Snakeroot can cause tremetol poisoning in humans. It is also poisonous to other mammals such as sheep, goats and horses.


If a cow eats snakeroot, it can be passed along in the meat or milk to make humans ill or worse. Long before current farming practices, cows came into contact with it in dry years where pasture land was unproductive or insufficient.


The cows searched out food where ever they could find it, like in woods. It took until the nineteenth century before farmers knew the plant was causing people to get ill or die. They then made the connection to their cattle and the milk production.


If in milk, it produces “milk sickness”.

Here is where it gets interesting. It was thought to be a possible cause of death of Mary Lincoln, Abraham Lincoln’s mother. She became ill after caring for some neighbors who were sick and was thought to have died from “milk sickness”. No one yet knew the cause of this illness. Thousands in the Midwest died of the poisoning before realizing White Snakeroot was to blame. Plants can be pretty dangerous if one does not know what they are.

About Garden Walk Garden Talk

I love to photograph, paint, draw, design, garden, travel the world, and pass on a few tips and ideas that I learned through experience as a Master Gardener and architect. I am highly trained in my field and enjoy my work each and every day. I garden in Niagara Falls, NY in zone 6-B. Find me at: http://gardenwalkgardentalk.com
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24 Responses to White Snakeroot

  1. acuriousgal says:

    Wow, Donna…I had no idea!! It’s a pretty plant, definitely not to be ingested

  2. acuriousgal says:

    Love the Cardinal pic too…so cute!!

  3. Shared on my new FB page and on g+

  4. Oh, I didn’t know about snakeroot and “milk sickness”…
    Have a beautiful new week, Donna and Monday!

  5. Well you learn something new everyday…thanks for passing this along.

  6. Hope says:

    Fascinating story. Thank you!

  7. connie661 says:

    Interesting story. Some people think “natural” means “safe,” but this illustrates vividly why that is not always the case.

  8. This plant is known in the horticultural world as Eupatorium rugosum and the cultivar ‘Chocolate’ is quite popular at garden centers and I have seen it in many gardens. I don’t like it because it seeds like crazy.

    • Roger Brook says:

      That’s interesting Carolyn. I am struggling to grow ‘Chocolate’, perhaps I should not bother
      We are constantly reminded of the toxicity of nature’s chemicals but spend our time worrying about man made pesticides such as glyphosate!
      Hope my Joe Pie weed Eupatorium purpureum is not toxic. Mine is magnificent this year.

      • The species is native to woodlands in the Eastern United States and the cultivar ‘Chocolate’ is poisonous in all parts of the plant I think just like the species. I have used it in client’s woodlands and like you Roger, have not seen the aggressive seeding. I do think the client’s gardeners cut it back in fall though. The plant will not grow true from seed and revert to the species from what I understand, so it is a good idea they deadhead the plant.

  9. Interesting read. I’ll keep an eye out for this since my daughter has sheep. Blessings, Natalie

  10. I find this growing as a weed in shrub hedges and other out of the way places. Not surprised it is up to no good.

  11. lucindalines says:

    Thank you for this information. A few years ago, I stopped buying random wild flower seed packets as I found several to have “flowers” that were actually considered noxious weeds by the farmers in the area. We are having quite a time with thistle in our back yard right now as a result. I am guessing that I need to be pretty vigilant nest summer, and I can probably get rid of most of it.

  12. Kevin says:

    Completely fascinating! Thanks for the heads up.

  13. Pat says:

    Interesting story about this pretty plant.

  14. bittster says:

    yikes! I think I have a bit of this around the wilder edges of the yard. This and I think boneset are both there and I thought they were poisonous….. I never knew how much though. I’m pretty sure the kids aren’t going to go around eating it, but this reminds me that it’s not a bad idea to tell them again not to stick stuff in their mouths even when playing around. Reminds me of the ‘don’t use oleander twigs to roast marshmallow’ stories we were told when little. Fascinating history btw!

  15. ‘Great minds think alike,’ Donna — I was about to do a posting on snakeroot as it abounds on our property. You beat me to it. I happen to like the way it looks in our Woodland Walk, but we have to be very vigilant, having grazing animals, because it gets into the pasture. Cutting it back before it goes to seed is a good strategy. P. x

  16. Phil Lanoue says:

    Very interesting and informative, I enjoyed reading this post.

  17. I had heard this about Lincoln’s mother, too. Also, it’s my understanding that it’s closely related to Boneset and Joe Pye Weed, too. The Latin names are changing, but at one point they were all in the Eupatorium genus. Here’s a good article about it: http://www.cpa.msu.edu/beal/plantofweek/plants/eupatorium_rugosum_20070910.pdf
    Apparently, butterflies like all of these, but the Snakeroot could be a problem for mammals, as you say. I think Cimifuga racemosa (Black Cohosh) is a different plant: http://www.illinoiswildflowers.info/woodland/plants/black_cohosh.htm. I have it (but not Snakeroot) in my garden.

  18. I am always learning something new when I read your posts – thanks so much for sharing! Happy Hump Day:)

  19. A.M.B. says:

    How interesting! It’s good to know what plants around me (and more importantly, around my children!) are poisonous.

  20. Interesting as always…it is important we know what is growing around us and in our gardens.

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