‘Tis the season for White Snakeroot (Ageratina altissima). This pretty, weedy plant can be found blooming in many of our forests from late summer “until frost.” Hm…that could be any day now, if you believe the weather reports!
One of the nice things about white snakeroot is that it is one of our native plants. According to my field guide, it is classified with the bonesets and Joe Pye weed – a Eupatorium. However, botanists, like birders, can be found reclassifying living organisms on an almost daily basis, it seems, and now this plant is in a separate genus: Ageratina.
I think that because we are surrounded these days with warnings about non-native invasive species, we tend to slip into the idea that native plants must all be good. In one sense they are: they are good for the ecological niche in which they have evolved. But this doesn’t make them “good” plants, necessarily. White snakeroot is an excellent example of this, for it is poisonous.
Back in the 19th century, many many people died from a disease that was labelled “milk sickness.” It seems that some milk (and, it turns out, meat) was tainted with something that made the cattle ill and killed people. The disease was known to wipe out large portions of early settlements (Abraham Lincoln’s own mother was one of its victims), and it became such a problem in parts of Kentucky that a $600 award was offered in the early 1800s to anyone who could find the cause of the disease.
Although not officially identified until 1928, legend has it that Dr. Anna Bixby (1809-1869) identified the causative agent long before that. Supposedly many of her patients were dying from milk sickness, and, as was probably fairly common at the time, the disease was blamed on witchcraft. Dr. Bixby knew there must be a more rational explanation, and noted that the disease only turned up in late summer and into the fall, and it seemed to be based on something the cattle were eating. One day she met up with a Shawnee woman who told her that white snakeroot was the culprit. Dr. Bixby fed a bit of the plant to a calf, which promptly displayed all the symptoms. She had all of the plant torn out from the fields and forests where cattle were grazing, and remarkably, the disease went away. Sadly, she never got credit for this (nor did the Shawnee woman).
What happens is that cattle eat white snakeroot when there is no other forage around, so it’s not like it’s a primary food choice for them. The plant contains tremetol, which is the poisonous compound. Tremetol is stored in the meat and milk, and thus it gets passed on to people who consume these cattle products.
That said, according to Daniel Moerman’s Native American Ethnobotany, the Cherokee and Iroquois did use this plant for a variety of medicines, including treatment for urinary ailments, as a diuretic, and as a treatment for venereal diseases. He doesn’t say, however, how well the medicines worked.
Still, just because a plant is toxic doesn’t mean we can’t enjoy it – just don’t eat it! As you walk through the woods, perhaps along a shady path, keep your eyes open for a scraggly-looking plant about three to five feet tall. The leaves are jagged, and the top has a flattened cluster of white flowers. If you are lucky, you may find some butterflies nectaring on it, for it is one of their foods. Take the time to get to know it, for it is a lovely plant. Then note where it is so you can be sure your cattle don’t graze upon it.