Common tansy (Tanacetum vulgare)

Description:

Appearance: Perennial herbaceous plant, 3' tall, up to 5' in shaded areas, and erect. A single stem branches extensively toward the top into short stems forming a flat-topped cluster of numerous button-like flower heads; plants have medicinal properties.

Leaves: Alternate, pinnately compound (leaflets arranged on both sides of a common stalk), irregularly lobed. Leaves become smaller towards the top of the stalk, and are strongly aromatic when crushed.

Flowers: Bright yellow daisy-like discs up to 0.5" wide, lacking rays, blooming from July through October.

Seeds: Numerous tufted seed dispersed by wind and water.

Roots: Spreads vegetatively forming new plants from even small root fragments.

Ecological Threat:

  • Common tansy is wide spread across most northern United States and Canadian provinces.
  • It is still cultivated in gardens and is common along roadsides and abandoned farmyards in northern Minnesota and along the north shore of Lake Superior. South sloping open areas are most vulnerable.
  • It was introduced to the United States from Europe for medicinal and horticultural purposes.
  • Common tansy is a MDA Prohibited noxious weed (Control List) in Minnesota.

 

Control Methods:

Grazing

  • Tansy is distasteful and even toxic to some grazing animals, however, one source claims that sheep graze it and are not affected

Chemical

  • Spot-spraying with selective broadleaf herbicide such as clopyralid, metsulfuron or 2,4-D

 

Native Substitutes:

 

Additional Resources