A Conversation about White Snakeroot and Tansy

Last week I talked about my houseplants. This week I'm focused on wild plants. I'm a pretty frugal person, and I'm of the opinion that if a plant reseeds itself into the fields and roadsides around me, I should be able to collect the seeds and relocate some into my own garden. Of course, this is the time of year for many plants to produce seeds. So I go out into the wilderness around my house with a knapsack full of envelopes and prescription bottles (empty) and any small containers that can be sealed up for the winter. And a sharpie because I have a memory like a sieve.

During my September dog-emptying strolls I spotted and admired a plant that had many interesting features. It had a chalky white flowerhead similar in shape to yarrow and leaves like Asters. It flowers very late in the season and thrives in dry shade as well as full sun. I marked a plant and waited for the seed heads. I also googled it to find its formal name (Ageratina altissima) and other features. Turns out there's good news and bad news. (There is another plant with the common name Virginia Snakeroot. AKA Aristolochia. Not at all similar) The good news is that it's a popular perennial pollinator plant, commonly known as White Snakeroot, and deer usually avoid it. This brings up the bad news... it's toxic. In fact notoriously so. The plant has a chemical, tremetol, that causes severe trembling and even death. It became infamous in the eighteen hundreds when cows grazed on the plant and settlers drank the milk which contained the toxin. Abraham Lincoln's mother (Nancy Hanks Lincoln) died of this “Milk Sickness” when he was nine years old. All I have to do is keep it away from kids and pets. Easy peasy.

The other free ranging perennial that caught my eye this year is Tansy (Tanacetum vulgare). All summer I passed a hayfield bordered by masses of these and I want some. Wikipedia describes the flower like this:  “corymb of flower heads with recognisable Fibonacci spirals.“ Pretty classy, eh? What it means is the flower is built like a broccoli floret. But the flower heads are much smaller , like tiny buttons,and bright yellow, and the leaves are shaped somewhat like ferns. The Fibonacci thing refers to the spiral formed by the seeds that is a geometric wonder. It looks like a teeny, tiny sunflower head with the seeds in spiral rows. 

The two have a couple of things in common. Maybe that's what drew my eye. Tansy can be toxic, too. It's valued by herbalists for many uses, but can be problematic. The toxin that belongs to Tansy is called thujone.  It has alkaloid content, called tanacetin, which makes it distasteful to animals.Like many herbs, the scent is  sharply distinctive, so it is rare that cattle (or deer) graze it.  Both Tansy and Snake Root are colonizers, which is a good thing because I want to plant them in a meadow. But if you want them in a more genteel type of garden, be sure to deadhead them to keep them in line.

Now, all these good and bad features must be considered, but these two plants are only mildly dangerous. Lots and lots of plants are just plain scary. Next week I'll talk about some wicked plants! Just in time for Halloween.

If you have comments or suggestions for future columns, contact me at jeanthepipper@duck.com.