Common tansy
Tanacetum vulgare L.
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
Family: Asteraceae (Sunflower)
Other Names: garden tansy, golden buttons
USDA Code: TAVU
Legal Status: Colorado Noxious Weed List B
Identification
Lifecycle: Perennial
Growth form: forb/herbaceous
Flower: 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/Fruit: Seeds are yellowish brown achenes with short, five-toothed crowns.
Leaves: Leaves are alternate, deeply divided into numerous narrow, individual leaflets.
Stems: Mature plants are 11/2- 6 ft tall. Stems are often purplish-red and extensively branched towards the top
Roots: Rhizomatous.
Other: Foliage emits a strong odor when crushed.
Impacts
Agricultural: 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 came impact forage quality and quantity.
Ecological: With adequate moisture common tansy will displace native and other desirable species.
Human: Can be toxic if large quantities are consumed.
Habitat and Distribution
General requirements: 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.
Distribution: Found throughout the United States.
Historical: 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.
Biology/Ecology
Life cycle: Perennial
Mode of reproduction: Reproduces by both seed and creeping rootstocks.
Seed production: listed as "prolific"
Seed bank: viability period unknown
Dispersal: Spread by seed movement, roots in infested topsoil and occasionally is found for sale (in violation with Colorado statute).
Integrated Management Summary
As with other rhizomatous perennials, mechanical controls such as mowing or hand cutting (Gloves and other protective clothing is recommended when pulling or handling common tansy, as the toxins can be absorbed through the skin) are most effective in combination with other methods.
Plants can sprout from severed roots, and cut stems may still produce viable seed. Control the spread of common tansy by preventing seed production and dispersal, minimizing the spread of cut rootstocks, and establishing healthy stands of desirable species on controlled areas.
Grazing areas with common tansy is not discouraged literature, but should be supervised closely to avoid "overuse" of desirable plants and to prevent stock from consuming a potentially harmful amount of common tansy.
Control
References
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
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