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Tansy Ragwort (2A)

(Senecio jacobaea)

Tansy Ragwort

(2A, Common in isolated areas of Montana)

(Senecio jacobaea)

Quick ID
  • Bright yellow daisy-like flowers, each 1” in diameter or less, 20-60 per cluster
  • Flowers generally have 13 petals
  • Some plants are 4’ tall or more
  • Leaves produce rank odor when crushed

Map Courtesy of Montana Natural Heritage Program, Tansy Ragwort – Low Suitability: 5% of Montana, Moderate: 1%, Optimal: 1%. Click here for larger image.

Tansy Ragwort plant image by Mike Bradeen, Lincoln County
Tansy Ragwort Plant

Video Information

Weed Images

Toxic Image
Tansy Wort plant image by Mike Bradeen, Lincoln County
Tansy Ragwort rosetta image by Mike Bradeen, Lincoln County
Tansy Ragwort flower
Tansy Ragwort leaf image by Mike Bradeen, Lincoln County
Tansy Ragwort - Photo by Leslie J. Mehrhoff, University of Connecticut,
Tansy Ragwort stem
Tansy Ragwort Invading - Photo by Eric Coombs, Oregon Department of Agriculture,

Weed Specifications

Weed Info
Type Information
Toxicity Toxic and can be lethal to cattle, horses, and deer, because of pyrrolizidine alkaloids in the plant
Best Management Practices Hand pulling before the plant goes to seed, digging getting the entire root, biocontrol, and herbicide *See additional documents below
Habitat Disturbed soil of open forest or meadows, often associated with timber harvest or fire, prefer cool, moist climates and 20” or more annual precipitation
Root Fibrous taproot, root fragments can produce new shoots
Leaves Deeply lobed, ruffled and green on top, lighter green on the underside, alternate, younger leaves have web-like hairs
Lifespan Biennial or short-lived perennial
Similar Looking Plants Common tansy, common groundsel, St. John’s wort
Important Information Each plant can produce 150,000 or more seeds and seeds can remain dormant in soil for 15 years, primarily reproduce by seeds but can also establish from vegetative buds, even populations thought to be eradicated must be monitored for several consecutive years

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