E-Flora BC: Electronic Atlas of the Flora of British Columbia

Senecio jacobaea L.
tansy ragwort (stinking willie)
Asteraceae (Aster family)

Introduction to Vascular Plants

© Jamie Fenneman  Email the photographer   (Photo ID #11417)

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Distribution of Senecio jacobaea
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Introduction

Tansy ragwort is an invasive introduced species from Europe that is now found in eastern and western North America, but is absent from the prairies and midwestern states (United States: CA, ID, IL, IN, MA, ME, MI, MT, NJ, NY, OR, PA, WA, WY; Canada: BC, MB, NB, NF, NS, ON, PE, QC) (USDA 2010). It is poisonous to livestock (BC Ministry of Agriculture 2009). Biological control methods have been applied to it, including the introduction of the cinnabar moth (tiger moth) (Tyria jacobaeae) to North America, a species which feeds exclusively on tansy ragwort. In our region, tansy ragwort can be confused with common tansy (Tanacetum vulgare), however, tansy ragwort has yellow ray petals, while common tansy lacks ray petals. Tansy ragwort was first recorded in British Columbia at Nanaimo in 1950 (BC Ministry of Agriculture 2009). Flora North America Online provides a detailed description for this species. Read more about this species in BC.

Species Information

Click on the image below to view an expanded illustration for this species.



General:
Biennial or short-lived perennial herb from a poorly-developed to evident taproot; stems erect, solitary or several, branched above, sparsely to densely white woolly-hairy, 0.2-1 m tall.
Leaves:
Basal leaves oblanceolate, stalked, 4-20 cm long including the stalk, 2-6 cm wide, mostly 2-3 times pinnately cut, thinly woolly-hairy when young but usually glabrous by flowering time; stem leaves similar, progressively reduced upwards, becoming unstalked.
Flowers:
Heads with ray and disk flowers, several to numerous in clusters; involucres 2-5 mm tall; involucral bracts oblanceolate, with long-pointed, usually black tips, hairless to sparsely woolly-hairy, margins translucent; bracteoles few, black-tipped; ray flowers yellow, 4-10 mm long; disk flowers yellow.
Fruits:
Achenes oblong, nerved, those of the disk flowers minutely coarse-hairy, those of the ray flowers glabrous; pappus of white hairlike bristles.

Source: The Illustrated Flora of British Columbia

Habitat / Range

Mesic to dry fields, clearcuts and pastures in the lowland zone; locally frequent on S Vancouver Island and adjacent lower mainland; introduced from Eurasia.

Source: The Illustrated Flora of British Columbia

Additional Notes

Tansy ragwort is considered an emerging invasive species in the Vancouver region by the Greater Vancouver Invasive Plant Council (2009). An emerging invasive species is defined by them as species "currently found in isolated, sparse populations but rapidly expanding their range within the region". It is listed as one of the top fourteen species of concern by the Coastal Invasive Plant Council. Visit their web site.

Ecology

Ecological Framework for Senecio jacobaea

The table below shows the species-specific information calculated from
original data (BEC database) provided by the BC Ministry of Forests and Range.
(Updated August, 2013)

Site Information
Value / Class

Minimum

Average

Maximum

Elevation (metres) 1370 1370 1370
Slope Gradient (%) 40 40 40
Aspect (degrees)
[0 - N; 90 - E; 180 - S; 270 - W]
220 220 220
Soil Moisture Regime (SMR)
[0 - very xeric; 4 - mesic;
8 - hydric]
3 3 3
Modal Nutrient Regime
Class
Number of field plots
 species was recorded in:
1
Modal BEC Zone Class
SWB
All BEC Zones (# of stations/zone) species was recorded in: SWB(1)

Climate

The climate type for this species, as reported in the: "British Columbia plant species codes and selected attributes. Version 6 Database" (Meidinger et al. 2008), is not evaluated, unknown or variable.

Taxonomic and Nomenclatural Links

Additional Photo Sources

Related Databases

Species References

BC Ministry of Agriculture and Lands. 2009. Tansy Ragwort. Available Online.

USDA. 2010. Plant profile for Senecio jacobaea. USDA Plants Database. United States Department of Agriculture. Available Online.

General References