Another wonderful article, I try to read them all by you.
I vaguely remembered reading about tansy as being toxic and not recommended for consumption anymore, so I looked it up on Wikipedia. The article includes a section on toxicity, and lists 4 identified compounds with various effects on people and other critters. Peterson's Field Guide to Edible Plants and an herb book both recommend limiting consumption, as it may have toxic effects in larger amounts. A more thorough search would probably turn up more information, but I read enough to recommend caution when using it.
I find it interesting how many strong smelling herbs people can eat that very few other critters can, and how easy it is grow many of these with very few problems.
I also caution against its use because it is not native, highly invasive, and therefore can misplace the native vegetation and the critters that depend on the native plants. Perhaps as a foundation planting where any strays get mowed over might work, or let it fight it out with some mints and other aggressive plants.
As always you are right on all counts, Lance, and I appreciate your added information. I debated adding a caution to the article and might still, but will wait till this evening when I have thought more about it.
My goals are to bring back the historical uses of a plant, only as cultural information. I hate like everything to be so repetitive, with cautions, etc.
But you are right, and I need to add that to the article because on the net, the articles are read as subject tags, and not collectively as they are read on DG.