Tansy Ragwort

(Click on an image below to see the captioned full-size version)
Figure 1		Figure 2		Figure 3		Figure 4		Figure 5		Figure 6
Figure 7		Figure 8

Scientific Name: Senecio jacobaea
Common Names: Tansy ragwort, Stinking Willie, Tansy Butterweed

Habitats:
Full sun or partial shade in pastures and fields, along roadsides, and in open disturbed areas. (Figure 1)
Tansy ragwort will tolerate a wide variety of soil types.

Key ID Features
	Herbaceous, biennial or short-lived perennial that reaches 8 in. to 3 ft. in height (Figures 2 and 3)
	In the first year a basal rosette of lobed leaves with a ruffled appearance is produced. Leaves range from 1.5-8 inches long and 0.75 to 2.25 inches wide (Figure 4)
	Stems branch near the top to bear numerous, yellow, daisy-like flowerheads. Tansy ragwort flowers from July through October (Figure 5)
	Each flower is composed of a central cluster of disc flowers surrounded by 10 to 15 ray flowers. (Figure 6)
	Fruits are light brown in color and very small (0.08 inch). Some seeds have a pappus (tuft of fluff like a dandelion seed) that aids in dispersion by wind. (Figure 7)
	This plant contains pyrrolizidine alkaloids which are toxic to cattle and horses.

Similar species:

Golden ragwort (Senecio aureus)
	Leaves are cordate (heart-shaped). (Figure 8)
	Leaves on the stem are greatly reduced compared to tansy ragwort.

Fact sheets and references:
Tansy Ragwort Identification: King County, Washington Noxious Weed Control Program
http://www.kingcounty.gov/environment/animalsAndPlants/noxious-weeds/weed-identification/tansy-ragwort.aspx

Best Management Practices Tansy Ragwort: King County, Washington Noxious Weed Control Program
http://your.kingcounty.gov/dnrp/library/water-and-land/weeds/BMPs/tansy_ragwort-control.pdf

Tansy Ragwort Weed Alert
http://your.kingcounty.gov/dnrp/library/water-and-land/weeds/Brochures/tansy_ragwort.pdf

Senecio jacobaea- Invasive Plant Atlas of New England: Description and great photos, history of the plant in New England, and similar species
http://www.eddmaps.org/ipane/ipanespecies/herbs/Senecio_jacobaea.htm

Information on toxicity of tansy ragwort to livestock: USDA, ARS Poisonous Plants Research Lab
http://www.ars.usda.gov/Services/docs.htm?docid=9988

Tansy ragwort: Washington State Noxious Weed Control Board
http://www.nwcb.wa.gov/detail.asp?weed=119

Field Guide to Noxious and Other Selected Weeds of British Columbia
http://www.agf.gov.bc.ca/cropprot/weedguid/tansyrag.htm

Tansy ragwort pictures, distribution maps, and additional resources: Forestry Images.
http://www.forestryimages.org/browse/subinfo.cfm?SUB=4418

last reviewed December 22, 2014