Common tansy identification and control
Common tansy is a Non-Regulated Class C noxious weed and control is not required in King County. It is often mistaken for tansy ragwort, which is regulated in King County. For more information on noxious weed regulations and definitions, see Noxious weed lists and laws.
Although common tansy is somewhat toxic, animals do not ingest it due to its strong odor, unlike tansy ragwort which is sometimes consumed by animals, especially when it is young, mixed in with hay, or after it has been cut.
Common tansy flowers are yellow just like tansy ragwort, but they look like buttons instead of daisies and do not have any ray petals. In contrast, tansy ragwort flowers are like yellow daisies with 13 ray petals and yellow centers. If you need assistance distinguishing these two plants, contact us and we can help you.
Additional information on common tansy
- Washington State Noxious Weed Control Board (external link)
- Common Tansy King County Best Management Practices (199 Kb Adobe Acrobat format).
What to do if you find this plant in King County, WashingtonBecause common tansy is so widespread, property owners in King County are not required to control it and we are not generally tracking infestations. We can provide advice on how to control common tansy, but there is generally no legal requirement to do so.
Common tansy photos