Weed Information: Tanacetum vulgare (tansy, common)
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Tanacetum vulgare (tansy, common)

Family: Asteraceae

Description

Common tansy was imported as a medicinal herb but has since been shown to be carcinogenic. It is an extremely aggressive, rhizomatous perennial which often forms monocultural stands in pasture and waste land. It is often confused with tansy ragwort because of misuse of the common name rather than any similarities between the plants. Common tansy is an aromatic perennial without ray flowers. Tansy ragwort is a non-aromatic biennial with ray flowers.

Characteristics

Flower Color
  • Orange
  • Yellow-orange
  • Yellow
Inflorescence Type (How the flowers are arranged on the plant)
  • Corymb
  • Head
Number of Petals
  • 0 (no petals)
  • 5 petals
  • more than 10 petals
Petal Separation
  • Completely free to base
  • United > 75% of length
Petal Tip
  • Pointed
Flower Symmetry
  • Flowers regular
Flower Length (Head length in the Asteraceae)
  • 5 mm (.20 inch)
  • 6 mm (.24 inch)
  • 7 mm (.28 inch)
  • 8 mm (.32 inch)
  • 9 mm (.36 inch)
Flower Width (Head width in the Asteraceae)
  • 7 mm (.28 inch)
  • 8 mm (.32 inch)
  • 9 mm (.36 inch)
  • 1.0 cm (.40 inch)
Number of Sepals
  • sepals lacking
  • more than 10 sepals
Sepal Separation
  • Completely free to base
Sepal Tip
  • Pointed
  • Rounded
Flower Sex
  • Bisexual (perfect)
Number of Styles
  • 1 style
Number of Stamens
  • 5 stamens
Stamens Attached to the Petals
  • Stamens attached to the petals
Stamens Connate (united)
  • Anthers united, syngynoecious

Carpel Separation
  • Carpels united (or one)
Number of Carpels
  • 1 carpel
Ovary Position
  • Inferior (epigynous)
Fruit Type
  • Achene
Fruit Length at Maturity
  • 1 mm (.04 inch) or less
  • 2 mm (.08 inch)
  • 3 mm (.12 inch)
Fruit Width at Maturity
  • 1 mm (.04 inch) or less
Burs
  • Fruit or seed NOT bur-like

Leaf Arrangement
  • Alternate
Leaf Type
  • Pinnately dissected
Stipules
  • Lacking
Tendrils
  • Tendrils absent
Venation
  • Pinnate
Petiole (leaf stem) Blade Ratio
  • Petiole absent (leaf sessile)
  • Petiole < 25% total length
Leaf Length (blade PLUS petiole)
  • 4 - 10 cm (1.60 - 4.0 inches)
  • 1 - 2 dm (4.0 - 8.0 inches)
  • 2 - 4 dm (8.0 - 16.0 inches)
Leaf Width
  • 2 - 4 cm (.80 - 1.6 inches)
  • 4 - 10 cm (1.6 - 4.0 inches)
Leaf Shape (simple leaves only)
  • Pinnately lobed
Leaf or Leaflet Margin
  • Dentate
  • Lobed
  • Parted
Leaf or Leaflet Blade Base
  • Acute (cuneate)
  • Acuminate (attenuate)
Leaf or Leaflet Tip
  • Acute
Leaf or Leaflet Blade Surface
  • Glabrous (NO hairs)
Succulence
  • Not succulent

Milky Juice
  • Juice NOT milky (watery)
Woodiness
  • Herbaceous
Spines or Thorns
  • Spines or Thorns ABSENT
Aromatic (vegetative structures)
  • Aromatic
Life Cycle
  • Perennial
Growth Habit (while flowering)
  • Erect, columnar (narrow)
Plant Height at Maturity
  • 4 - 6 dm (1.3 - 2.0 feet)
  • 6 - 8 dm (2.0 - 2.6 feet)
  • 8 - 10 dm (2.6 - 3.3 feet)
  • 1 - 1.5 meters (3.3 - 5.0 feet)
Wind Dissemination
  • Not wind disseminated
Moisture Regime
  • Seasonally saturated
  • Mesic
Chlorophyll
  • Present

Stem Cross Section
  • Round
Flowering Stem Leaves
  • Stem uniformly leafy
Main Stem Branches
  • Main stem branched

Root or Vegetative Propagule
  • Rhizomatous

US State
  • Arkansas
  • Connecticut
  • Delaware
  • Illinois
  • Kansas
  • Kentucky
  • Louisiana
  • Massachusetts
  • Maine
  • Michigan
  • Missouri
  • Mississippi
  • North Carolina
  • New Hampshire
  • New Jersey
  • New York
  • Ohio
  • Pennsylvania
  • Tennessee
  • Virginia
  • Wisconsin
  • West Virginia
  • Hawaii
  • Indiana
  • Maryland
  • Rhode Island
  • Vermont
  • Alaska
  • Arizona
  • California
  • Colorado
  • Iowa
  • Idaho
  • Minnesota
  • Montana
  • North Dakota
  • New Mexico
  • Nevada
  • Oklahoma
  • Oregon
  • South Dakota
  • Utah
  • Washington
  • Wyoming
  • Nebraska
Canadian Province or Territory
  • British Columbia
  • New Brunswick
  • Nova Scotia
  • Ontario
  • Prince Edward Island
  • Quebec
  • Alberta
  • Manitoba
  • Newfoundland
  • Saskatchewan
  • Yukon
  • Northwest Territory
Other
  • District of Columbia
  • St. Pierre and Miquelon
  • Labrador

  • Common Weeds of the Canadian Prairies, 1963 (Cat# A53-1136-1) See page: 63
  • Gilkey`s Weeds of the Pacific Northwest, 1980 (ISBN 0-88246-039-0) See page: 353
  • How to Know the Weeds, 1972, (ISBN# 0-697-04880-2) See page: 169
  • Northwest Weeds, 1990 (ISBN 0-87842-249-8) See page: 123
  • Ontario Weeds, 1992 Agdex 640, Publication #505 See page: 220
  • Selected Weeds of Oregon, 1985 and 1989 Supplement (s) Oregon State Dept. of Agriculture, See page: 95
  • South Dakota Weeds, 1967 South Dakota State University, See page: 197
  • South Dakota Weeds 2002 South Dakota Dept. of Ag. 523 E. Capitol, Foss Bldg. Pierre, South Dakota 57501 See page: 201
  • Weeds, 1955 (1980) Walter Conrad Muenscher, ISBN# 0-8014-1266-8 See page: 499
  • Weeds and Poisonous Plants of Wyoming and Utah 1987 (ISBN 0-941570-06-1) See page: 212
  • Weeds of Alberta, 1983 Alberta Environmental Centre Agdex 640-4, See page: 199
  • Weeds of California, 1970, State of California Publications and Documents. See page: 502, 503
  • Weeds of California and other Western States, 2007 (ISBN 13: 978-1-879906-69-3) See Page: 407
  • Weeds of Canada, 1970 Canada Dept. of Ag., Pub. # 948, See page: 180
  • Weeds of Colorado, 1990 Cooperative Extension, Colorado State Univ. Bulletin 521A, See page: 154
  • Weeds of Eastern Washington and Adjacent Areas, 1972 (LOC 72-83635) See page: 330
  • Weeds of the Midwestern United States & Central Canada, University of Georgia 2010, ISBN#0-8203-3506-1 See page: 128
  • Weeds of the North Central States, 1981 Univ. of Illinois, Urbana - Champaign Bulletin # 772, See page: 236
  • Weeds of the Northeast, 1956, Univ. of Delaware Field Manual #1 See species #: 286
  • Weeds of the Northern United States and Canada, 1964 Montgomery See page: 191
  • Weeds of the Northern U.S, and Canada, 1999 Royer and Dickinson, (ISBN# 1-55105-221-0) See page: 58 - 59
  • Weeds of the South, University of Georgia 2009, ISBN#0-8203-3046-9 See page: 109
  • Weeds of the West, 1992 (ISBN 0941570-13-4) See page: 184
  • Weeds of the West, 2000 (ISBN 0941570-13-4) See page: 184
  • Weeds of Utah, 1971 UAES Special Report 21, See page: 107
  • Wildly Successful Plants, A Handbook of North American Weeds, 1977 (ISBN# 0-02-528850-4) See page: 25, 165
  • Listed as a `Weed` by the Biota of North America Program, 2008 x
  • Listed in the WSSA Composite List of Weeds X
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