Tanacetum vulgare (Common Tansy)
|Also known as:||Golden-buttons|
|Habitat:||part shade, sun; disturbed soil, fields, ditches, roadsides|
|Bloom season:||July - September|
|Plant height:||1 to 5 feet|
|Wetland Indicator Status:||GP: FACU MW: UPL NCNE: FACU|
|MN county distribution (click map to enlarge):|
|National distribution (click map to enlarge):|
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20 to 200 flowers in flat clusters up to 4 inches across at the top of the plant and arising from the upper leaf axils. Individual flowers look like golden yellow buttons, about ¼ inch across. There are no petals (ray flowers), only tiny center disc flowers.
Leaves and stem:
Leaves are feathery or fern-like, up to 8 inches long, compound in 4 to 10 pairs of leaflets. Leaflets are up to 1½ inch long, hairless, stalkless, with sharply toothed lobes and dotted glands. There is a pungent odor when the leaves are crushed. Attachment is alternate. Stems are ridged, hairless or sparsely hairy, and tinged red.
Common Tansy is a good example of a cultivated, non-native plant that escapes into the wild and goes unnoticed until one day, BOOM, it's everywhere and it's too late to do anything about it. The first collection record in Minnesota was in 1875. On our county distribution map, you could probably draw a solid line all along the north shore of Lake Superior from south of Duluth past Grand Marais and you wouldn't be far from the mark. You can drive along almost any county road in Lake or St. Louis county and spot large masses of it. It has spread far and wide beyond the Arrowhead and is quickly making its way west and south. Tansy is on Minnesota's "control" noxious weed list, which means efforts are supposed to be made to control its spread, but there aren't really any programs in place to make that happen, let alone eradicate it. A bio control is being investigated but it will be years of research and testing before a suitable one is found (assuming one is found at all), and we can only imagine how much worse the problem will be by then. Besides, bio controls of other species have not resulted in eradication and we don't have our hopes up it will be much different with Tansy, but just maybe we will get lucky with this one. Cross your fingers. Some have had success with grazing sheep and goats. Tansy does respond to herbicides but it takes repeated treatment, as does pulling since root fragments can resprout. If pulling, wearing gloves is recommended to avoid possible skin reactions
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- Common Tansy plants
- a clump of Tansy
- leaves emerging in spring
- roadside Tansy
- Tansy along Lake Superior
- Tansy run amok
Photos by K. Chayka taken in Lake and Ramsey counties. Other photos courtesy Peter M. Dziuk.
Have you seen this plant in Minnesota, or have any other comments about it?