This plant’s common name is White snakeroot. Its scientific name is Ageratina altissima. Here’s another photo of a single plant. If you look closely, you can see that the lower leaves have stalks while the upper leaves do not.
This closeup view shows an upper leaf with a developing flower stalk from the leaf’s axil.
Next, we have the top of the plant with developing flower clusters . . .
The White snakeroot flowers are beginning to bloom . . .
Look closely at the individual flowers of the White snakeroot.
Each tiny flower grows in a flower head (like “flowers within a flower”) which is typical of a plant in the Asteraceae family.
Now here’s an intriguing piece. When I studied White snakeroot, I was struck by its flower which immediately reminded me of Boneset (Eupatorium perfoliatum). Here are two photos of Boneset . . . the first shows the upper part of the plant with its leaves surrounding the stem and with the developing flower clusters:
And this second photo shows the Boneset flower head and flowers up close:
You can see the similarities between the White snakeroot and the Boneset flowers. When I first learned the scientific name for White snakeroot, it was Eupatorium rugosum. And Boneset was (and remains) Eupatorium perfoliatum. With the on-going study and re-classification of plants, White snakeroot was moved from the Eupatorium genus to the Ageratina genus and was given a new species name (altissima).
Thanks for this great comparison. I knew they were related by looking at the flowers but didn’t realize they were once in the same genus.
Thank you for your interesting post. Your photo of boneset, though, does not show the characteristic perforation of the leaf cluster by the stem
http://www.wqed.org/birdblog/2010/08/18/summer-beauty-boneset/
Can you post another photo to clarify, please?
Monica, my intention with this particular post was to highlight White snakeroot so I chose to not post lots of Boneset photos. I do have Boneset on my list of plants to feature in a plant portrait video sometime soon. The photo you’re requesting will be included in that video.
I have dairy goats and have just been informed about White Snakeroot and Milk Sickness. If the goats eat it (literature says cows and sheep) they will get sick and so will we if we drink the milk. This killed people in pioneer days.
We are having mixed identification of the plants. Your comparison will help me with a definite differentiation.
But do you know if Milk Sickness is associated with White Snakeroot, Boneset or both?
I do not know. I suggest asking someone at the county agricultural extension office (if you are in the U.S.).