Senecio jacobaea
Senecio ertterae
stinking willie, tansy ragwort
ertter's groundsel, ertter's ragwort
sparsely and unevenly tomentose, glabrescent except in leaf axils and among heads.
(± turgid or subsucculent) unevenly villous-tomentose, glabrescent.
(often purplish-tinged) usually single, sometimes loosely clustered.
usually single, rarely clustered.
± evenly distributed (basal often withering before flowering); petiolate (sometimes obscurely);
blades ovate to broadly ovate (usually 1–3-pinnate, lobes mostly obovate to spatulate), (4–)7–20(–30) × (1–)2–5(–12) cm, bases usually tapered, ultimate margins dentate (distal leaves similar, smaller).
progressively reduced distally (basal usually withering before flowering); petiolate (petioles winged);
blades oblanceolate to spatulate, 4–7 × 1.5–3 cm, bases tapered, margins incised (distal leaves sessile, bractlike).
± 13;
corolla laminae 8–12 mm.
± 8 (± 13?);
corolla laminae 5–6 mm.
± 13, 3–4(–5) mm, tips black or greenish.
± 13, 6–7 mm, tips green.
of 2–6 (inconspicuous) bractlets (less than 2 mm).
of 1–5+ linear to subulate bractlets (to 4 mm).
(10–)20–60+ in corymbiform arrays.
6–10(–20) in cymiform arrays.
all sparsely hairy or ray cypselae glabrous.
usually hairy (especially on angles), sometimes glabrous.
= 40.
= 40.
Senecio jacobaea
Senecio ertterae
Senecio jacobaea is a weed introduced from Europe and now well established in places of cool, damp summers. It is toxic to livestock and legally noxious in most states and provinces where it occurs.
The Russian botanist E. Wiebe (2000) resuscitated Jacobaea for plants that are treated here as Senecio jacobaea, S. erucifolius, and S. cannabifolius. Phylogenetic studies may confirm the utility of recognizing Jacobaea as a distinct genus; to do so here would be premature.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
Of conservation concern.
Senecio erterrae is in the Center for Plant Conservation’s National Collection of Endangered Plants.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
- Local floras:
BC, 
CA, 
OR, 
WA - Local Web sites: CalFlora, CalPhotos,
Flora NW, 
Go Botany, 
IL Wildflowers, 
MI Flora, 
PNW Herbaria, Turner Photog. 
WildflowerSearch
iNaturalist (observations)
USDA Plants Database- LBJ Wildflower Center
- SEINet
- Plants of the World Online
- Encyclopedia of Life
- Wikipedia
- Google Image Search
