Weed Information: Jacobaea vulgaris (ragwort, tansy)
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Jacobaea vulgaris (ragwort, tansy)

Family: Asteraceae

Description

One of the most poisonous plants to horses. This erect, fibrous-rooted biennial is very competitive in pastures. The leaves are irregularly dissected, and the small flower heads often have 13 ray flowers. The bracts beneath the flowers have the small, black tips typical of the genus.

Characteristics

Flower Color
  • Orange
  • Yellow-orange
  • Yellow
Inflorescence Type (How the flowers are arranged on the plant)
  • Corymb
  • Cyme (simple or branched)
  • Head
Number of Petals
  • 5 petals
  • more than 10 petals
Petal Separation
  • Completely free to base
  • United > 75% of length
Petal Tip
  • Bilobed
  • Rounded
Flower Symmetry
  • Flowers regular
Flower Length (Head length in the Asteraceae)
  • 3 mm (.12 inch)
  • 4 mm (.16 inch)
  • 5 mm (.20 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)
  • 1.5 cm (.60 inch)
  • 2.0 cm (.80 inch)
Number of Sepals
  • sepals lacking
  • 10 sepals
  • more than 10 sepals
Sepal Separation
  • Completely free to base
Sepal Tip
  • Pointed
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
  • Simple (including lobed leaves)
Stipules
  • Lacking
Tendrils
  • Tendrils absent
Venation
  • Pinnate
Petiole (leaf stem) Blade Ratio
  • Petiole absent (leaf sessile)
  • Petiole < 25% total length
  • Petiole 25% - 75% total length
Leaf Length (blade PLUS petiole)
  • 2 - 4 cm (.80 - 1.60 inches)
  • 4 - 10 cm (1.60 - 4.0 inches)
  • 1 - 2 dm (4.0 - 8.0 inches)
Leaf Width
  • 2 - 4 cm (.80 - 1.6 inches)
  • 4 - 10 cm (1.6 - 4.0 inches)
Leaf Shape (simple leaves only)
  • Obovate
  • Oval
  • Ovate
  • Pinnately lobed
Leaf or Leaflet Margin
  • Dentate
  • Lobed
  • Parted
Leaf or Leaflet Blade Base
  • Oblique
  • Truncate
Leaf or Leaflet Tip
  • Acute
  • Rounded (obtuse)
Leaf or Leaflet Blade Surface
  • Floccose
  • Glabrous (NO hairs)
  • Tomentose
Succulence
  • Not succulent

Milky Juice
  • Juice NOT milky (watery)
Woodiness
  • Herbaceous
Spines or Thorns
  • Spines or Thorns ABSENT
Aromatic (vegetative structures)
  • Not aromatic
Life Cycle
  • Biennial
  • Perennial
Growth Habit (while flowering)
  • Erect, columnar (narrow)
  • Erect, spherical (bushy)
Plant Height at Maturity
  • 2 - 4 dm (8.0 - 16.0 inches)
  • 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
  • Fruit, seed, or spore wind borne
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
  • Fibrous

US State
  • Illinois
  • Massachusetts
  • Maine
  • Michigan
  • New Jersey
  • New York
  • Pennsylvania
  • Indiana
  • California
  • Idaho
  • Montana
  • Oregon
  • Washington
  • Wyoming
Canadian Province or Territory
  • British Columbia
  • New Brunswick
  • Nova Scotia
  • Ontario
  • Prince Edward Island
  • Quebec
  • Manitoba
  • Newfoundland
Other
  • St. Pierre and Miquelon

  • The Biology of Canadian Weeds: Canadian Journal of Plant Science Vol:71Pg.127
  • California Growers Weed Identification Handbook, 1968 - 1998 University of California Publication # 4030-1, See page: 212
  • Common Weeds of Canada, Mulligan 1987 (ISBN 0-910053-59-9) See page: 128
  • Common Weeds of the Canadian Prairies, 1963 (Cat# A53-1136-1) See page: 58
  • Common Weeds of the United States, 1971 (ISBN 0-486-20504-5) See page: 428
  • Gilkey`s Weeds of the Pacific Northwest, 1980 (ISBN 0-88246-039-0) See page: 359
  • Northwest Weeds, 1990 (ISBN 0-87842-249-8) See page: 133
  • Ontario Weeds, 1992 Agdex 640, Publication #505 See page: 224
  • Selected Weeds of Oregon, 1985 and 1989 Supplement (s) Oregon State Dept. of Agriculture, See page: 90
  • S.W.S.S. Weed ID Guide, 1993 Section Number and Five letter code: 13 SENJA
  • Weeds, 1955 (1980) Walter Conrad Muenscher, ISBN# 0-8014-1266-8 See page: 493
  • Weeds, A Golden Guide, 1972 ISBN#0-307-24353-2 See page: 140
  • Weeds and Poisonous Plants of Wyoming and Utah 1987 (ISBN 0-941570-06-1) See page: 204
  • Weeds of California, 1970, State of California Publications and Documents. See page: 492, 493
  • Weeds of California and other Western States, 2007 (ISBN 13: 978-1-879906-69-3) See Page: 382
  • Weeds of Canada, 1970 Canada Dept. of Ag., Pub. # 948, See page: 181
  • Weeds of Nova Scotia, 1986 (ISBN# 0-88871-063) See page: 68
  • Weeds of the Northeast, 1997 Cornell University ISBN# 0-8014-8334-4 See page: 154
  • Weeds of the Northern United States and Canada, 1964 Montgomery See page: 189
  • Weeds of the Northern U.S, and Canada, 1999 Royer and Dickinson, (ISBN# 1-55105-221-0) See page: 59
  • Weeds of the West, 1992 (ISBN 0941570-13-4) See page: 166
  • Weeds of the West, 2000 (ISBN 0941570-13-4) See page: 166
  • 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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