Keys to Identification
- Button shaped flowerheads lack petals
- Foliage is strong smelling when crushed
- Slender leaflets
This information courtesy of the Colorado Natural Areas Program.
Garden tansy, golden buttons
Colorado Noxious Weed List B
Yellow flowers are numerous in flat-topped dense clusters at the tops of the plants. Buttonlike flower heads lack ray flowers. July to September.
Seeds are yellowish brown achenes with short, five-toothed crowns.
Leaves are alternate, deeply divided into numerous narrow, individual leaflets.
Mature plants are 11/2- 6 ft tall. Stems are often purplish-red and extensively branched towards the top.
Foliage emits a strong odor when crushed.
Common tansy is considered undesirable forage for livestock. The plant is considered toxic; fortunately animals rarely ingest it as it is very unpalatable. Common tansy can impact forage quality and quantity.
With adequate moisture common tansy will displace native and other desirable species.
Can be toxic if large quantities are consumed.
Habitat and Distribution
Common tansy is commonly found along roadsides, stream and irrigation ditch banks, in waste places, ornamental beds and in pastures. It grows best in full sun and on fertile, well-drained soil.
Found throughout the United States.
Common tansy is a native of Europe that was introduced into North America as an ornamental and medicinal herb (Whitson et al. 1996). It has been used over the centuries for treating various ailments and as an insect repellent.
Mode of reproduction
Reproduces by both seed and creeping rootstocks.
Listed as “prolific.”
Viability period unknown.
Spread by seed movement, roots in infested topsoil and occasionally is found for sale (in violation with Colorado statute).
Colorado Natural Areas Program. 2000. Creating an Integrated Weed Management Plan: A Handbook for Owners and Managers of Lands with Natural Values. Colorado Natural Areas Program, Colorado State Parks, Colorado Department of Natural Resources; and Division of Plant Industry, Colorado Department of Agriculture. Denver, Colorado. 349 pages.
Dow AgroSciences. 1998. Common tansy-biennials/perennials. Dow AgroSciences. The Ranch, Pasture Improvement. Available: http://www.dowagro.com/theranch/weedres.htm
LeCain, R. & Sheley, R., Montana State University Extension Service (12/2002). Common tansy (Tanacetum vulgare). (Publication No. MT199911 AG) Retrieved October 18, 2005 from http://www.montana.edu/wwwpb/pubs/mt9911.pdf
Whitson, T.D.(ed.), L.C. Burrill, S.A. Dewey, D.W. Cudney, B.E. Nelson, R.D. Lee, R. Parker. 1996. Common tansy. Weeds of the West. Western Society of Weed Science, in cooperation with the Western United States Land Grant Universities Cooperative Extension Services, Newark CA. pg. 184