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Class C Noxious Weed

Common tansy
Tanacetum vulgare
 

Image of common tansy

Other common names:  Garden tansy
 Plant family: Asteraceae (Sunflower family)
Year listed: 1988
Native to: Europe

Why is it a noxious weed?

Common tansy is an undesirable as forage for livestock.

How would I identify it?
General Description: Aromatic perennial with fern like foliage and yellow button-like flowers.

Leaves:

  • Alternate, Example of alternate leavespinnately compound (leaflets arranged on both sides of a common stalk), deeply divided into numerous narrow, toothed segments.
  • Leaves become smaller towards the top of the stalk, and are strongly aromatic when crushed.

Flowers:

  • Numerous button-like yellow flowers, 1/4 to 1/2 inches across, in flat-topped dense clusters. No ray flowers.

Stems:

  • Multiply brown to reddish-brown stems, dotted with glands.

How does it reproduce?
Common tansy reproduces by numerous tufted seed dispersed by wind and water and vegetatively by forming new plants from root fragments.

Where does it grow?
Common tansy is generally found along roadsides, waste areas, stream banks, and in pastures.

What is the distribution in Washington State?

How do I control it?

General control methods:

Cultural:

  • Remove plant seeds from personal gear, equipment, machinery, vehicles, and animals before leaving an infested area
  • Minimize soil disturbance and re-vegetate any disturbed areas promptly
  • Maintain a healthy native plant community
  • Monitor and identify areas where invasions of common tansy is likely

Herbicide: It is best to cut the stems off, dispose of them properly, then apply the appropriate herbicide to the stump. Please refer to the PNW Weed Management Handbook, or contact your county noxious weed coordinator.

Mechanical:

  • Mowing or cutting infestations before flowering and seed-set occur to eliminate seed production
  • Multiple treatments will be required to exhaust the plant's resources
  • Monitor treatment success continuously over successive years

 Biological: None known.

Are there plants that may be confused with (name of weed)?

Often confused with tansy ragwort (Senecio jacobaea) that has ray flowers.

For more information

View the WSU Extension Common Tansy Fact Sheet here.

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Image of common tansy's button-like yellow flowers Image of common tansy plants
Button-like yellow flowers of common tansy.

Image courtesy of Stevens Co. Noxious Weed Control Board.		 Common tansy plants.


Image courtesy of Ben Legler.

 Last updated August 26, 2008