Senecio jacobaea

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Legend for Species Pages

Tansy Ragwort

Senecio jacobaea L.

Synonym: Jacobaea vulgaris Gaertn.

  • Present in Alberta – reported, not confirmed
  • Moss, Flora of Alberta – No
  • Global Invasive Species Database – No
  • NatureServe Rank – Low
  • Haber, Upland – No
  • Haber, Wetland – No
  • CWF, Status & Invasive Range – No
  • Alberta Revegetation Guidelines – No
  • The Nature Conservancy – Yes, w/ ESA
  • CBCN – No
  • AB Weed – Prohibited Noxious

Remarks

This species has been reported in Alberta, but as far as is known all such instances have been due to misidentification. Natureserve lists for BC SK WA and ID.

Reported in Edmonton in 2006, see IRIS No.53 [1] December 2006, Page 7. This report was subsequently corrected.

Leaves are pinnate, with obovate or spatulate lobes also pinnate (2-3 pinnatifid), a herbaceous perennial with possibly woody taproot or caudex at summit of taproot, foliage is glabrous or unevenly soft-hairy, not sticky, flower heads are 3-15+ mm in diameter, usually 10 to 20 but can be as many as 60 in number, flowers are yellow, basal leaves wither before flowering, bracts of flower-heads consist of 2-6 very small (2 mm) bractlets at the base with 13 or so 3-4(or 5)mm long bracts surrounding the florets, leaves on stem are all more or less the same size, stems may be tinged with purple, grows mostly in disturbed sites with intermittent moisture or in dry soils (mesic to xeric).

Poisonous: contains several alkaloid poisons, can poison livestock.

The native S. congestus is sometimes mistakenly identified as S. jacobaea since from a distance there is some resemblance. However, S. congestus grows in moist soils, commonly seen as a ring of plants around a slough margin, its basal leaves are entire, not pinnately divided, and are present at flowering, it is an annual or biennial with a taproot. The stems are soft and hollow. See USDA Plants [2] and Flora of North America [3].

Another native, Senecio eremophilus, can more easily be mistaken to be S. jacobaea. It has leaves that are usually merely toothed, not pinnate, but they can be once-pinnate, so some overlap in appearance with tansy ragwort is possible. The two are otherwise quite similar. See USDA Plants [4]. See also [5]. Identification should be confirmed before control measures are taken.

[6] Link to USDA Plants Profile, Senecio jacobaea(L.) stinking willie

[7] Link to NatureServe I-Rank information for Senecio jacobaea(L.) - Tansy Ragwort


Senecio jacobaea(L.) Britton, N.L., and A. Brown. 1913. An illustrated flora of the northern United States, Canada and the British Possessions. Vol. 3: 542. Courtesy of Kentucky Native Plant Society.

[8] Link to USDA Germplasm Resources Information Network.

[9] Link to Flora of North America.