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Photo Credit: Steve Dewey, Utah State University, Bugwood.org -
Photo Credit: Jan Samanek, Phytosanitary Administration, Bugwood.org
Also known as: common tansy, golden-buttons, garden tansy
Originally brought to North America from Eurasia in the 1600s, common tansy has slowly spread westward over time. It primarily infects pastures and displaces desirable forage plants.
Description:
| Life Cycle: | Perennial (life cycle lasts more than one year) |
| Early Detection and Rapid Response species: | No |
| Height: | 1 – 5 feet (.3 – 1.5 meters) |
| Leaf Description: | Fern-like foliage with narrow, toothed leaves. They become smaller towards the top of the stalk and produce a strong aroma when crushed. |
| Fruit & Flower Description: | Flowers are yellow and button-like and arranged in flat-topped clusters. It produces lightweight seeds that can be dispersed by wind, water, and equipment. |
| Bloom Time: | June to August |
Habitat:
- Generally found along roadsides, streambanks, and in pastures.
- It grows in a variety of soil types and light conditions.
Impact:
- Highly invasive and can severely reduce pasture capacity and desirable forage.
- It is reportedly poisonous to livestock, though it is seldom grazed due to its strong odor.
What you can do about it:
- Prevention is the best control – make sure to remove all seeds from personal gear, equipment, and animals before leaving an infested area.
- Mowing before the plant produces flowers and seeds is beneficial. Repeated mowing is required to keep plants from re-sprouting.
- Small infestations can be hand pulled or dug up. This is easiest and most effective in the spring after a rain when the ground is damp and before the plant has produced seeds.
Look-alikes:
Common tansy is often confused with a couple other invasive species: St. John’s wort (Hypericum perforatum) and tansy ragwort (Jacobaea vulgaris). Unlike tansy ragwort and St. Johns wort, common tansy flowerheads are button-like and does not have petals.
Noxious Weed Listing:
| State of Oregon: | Not listed |
| State of Washington: | Class B |
More Resources:
Download the Common Tansy Best Management Practices Factsheet
- Pacific Northwest Weed Management Handbook: Common tansy
- University of California, Weed Research & Information Center: Common tansy