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 can impact forage quality and quantity.

Ecological

With adequate moisture common tansy will displace native and other desirable species.

Ecological

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).

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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