OregonFlora: Senecio jacobaea vs. Senecio sylvaticus

	Senecio jacobaea	Senecio sylvaticus
	stinking willie, tansy ragwort	wood groundsel, woodland ragwort
Habit	Herbs perennial, 2–8(10) dm; caudices ± woody, branching, rhizomatous.	Herbs annual, (1.5)3–8+ dm; from fibrous taproots.
Stems	1, or rarely 2–4 and loosely clustered, often purple-tinged, sparsely and unevenly tomentose.	1, densely pubescent with abundant curly hairs.
Leaves	basal usually withering before flowering; cauline ± evenly distributed along stems; distal slightly smaller; ovate to broadly ovate, bases tapered, usually 1–3-pinnate, ultimate margins dentate; lobes obovate to spatulate, petiolate.	evenly distributed along stems, obovate to oblong in outline, bases tapering, usually 1–2-pinnately lobed or divided, ultimate margins dentate; proximal petiolate; distal clasping and bract-like.
Inflorescences	compound corymb-like arrays; bracts conspicuous but small.	corymb-like arrays; bracts 0 or inconspicuous.
Involucres	widely cylindric or urn-shaped.	cylindric.
Ray florets	~13; rays 8–12 mm.	0, rarely 1–8; rays 1–2+ mm.
Disc florets	60–70+.	40–50.
Phyllaries	13, 3–4(5); tips black or dark green.	13+, rarely 21, 4–7+ mm; tips green or minutely black.
Calyculi	2–6 bractlets, inconspicuous, usually < 2 mm.	0 or 1–5+ linear to filiform bractlets, 2–3 mm.
Fruits	0.75–1.3 mm, sparsely hairy or glabrous.	1.5–2.5 mm, sparsely pubescent on ribs.
Heads	(10)20–60+.	12–24.
2n	=40.	=40.

	Senecio jacobaea	Senecio sylvaticus
Distribution	[WildflowerSearch map]	[WildflowerSearch map] [BONAP county map]
Discussion	Disturbed areas, pastures, roadsides. Flowering May–Sep. 0–1600 m. Casc, CR, Est, Sisk, WV. CA, ID, WA; north to British Columbia, northeast to MT, northeastern North America; Europe. Exotic. Senecio jacobea is an introduced weed, originally from Europe. It establishes in places with cool, wet summers and is particularly toxic to livestock. In most states where it occurs, this species has been declared a noxious weed.	Disturbed open wooded areas. Flowering May–Oct. 0–1200 m. Casc, CR, ECas, Est, Sisk, WV. CA, WA; north to British Columbia, scattered in eastern North America; Asia, Europe. Exotic. Senecio sylvaticus is a native of Eurasia and favors cool, damp climates. In overall appearance, it resembles the more common S. vulgaris. However, the latter has distinctive black-tipped phyllaries, while S. sylvaticus has phyllaries that are generally green-tipped. This species is well established in the Pacific Northwest and in parts of eastern Canada. Elsewhere it is sporadic.
Source	Flora of Oregon, volume 2, page 340 Debra Trock	Flora of Oregon, volume 2, page 341 Debra Trock
Sibling taxa	S. aronicoides, S. crassulus, S. ertterae, S. fremontii, S. hydrophiloides, S. hydrophilus, S. integerrimus, S. serra, S. sphaerocephalus, S. sylvaticus, S. triangularis, S. viscosus, S. vulgaris	S. aronicoides, S. crassulus, S. ertterae, S. fremontii, S. hydrophiloides, S. hydrophilus, S. integerrimus, S. jacobaea, S. serra, S. sphaerocephalus, S. triangularis, S. viscosus, S. vulgaris
Synonyms	Jacobaea vulgaris
Web links	Local floras: BC, CA, OR, WA Local Web sites: CalFlora, CalPhotos, Flora NW, 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	Local floras: BC, CA, OR, WA Local Web sites: CalFlora, CalPhotos, Flora NW, PNW Herbaria WildflowerSearch iNaturalist (observations) USDA Plants Database LBJ Wildflower Center SEINet Plants of the World Online Encyclopedia of Life Wikipedia Google Image Search

Senecio sylvaticus

stinking willie, tansy ragwort

wood groundsel, woodland ragwort

Habit

Herbs perennial, 2–8(10) dm; caudices ± woody, branching, rhizomatous.

Herbs annual, (1.5)3–8+ dm; from fibrous taproots.

Stems

1, or rarely 2–4 and loosely clustered, often purple-tinged, sparsely and unevenly tomentose.

1, densely pubescent with abundant curly hairs.

Leaves

basal usually withering before flowering;

cauline ± evenly distributed along stems;

distal slightly smaller; ovate to broadly ovate, bases tapered, usually 1–3-pinnate, ultimate margins dentate;

lobes obovate to spatulate, petiolate.

evenly distributed along stems, obovate to oblong in outline, bases tapering, usually 1–2-pinnately lobed or divided, ultimate margins dentate;

proximal petiolate;

distal clasping and bract-like.

Inflorescences

compound corymb-like arrays;

bracts conspicuous but small.

corymb-like arrays;

bracts 0 or inconspicuous.

Involucres

widely cylindric or urn-shaped.

cylindric.

Ray florets

~13;

rays 8–12 mm.

0, rarely 1–8;

rays 1–2+ mm.

Disc florets

60–70+.

40–50.

Phyllaries

13, 3–4(5);

tips black or dark green.

13+, rarely 21, 4–7+ mm;

tips green or minutely black.

Calyculi

2–6 bractlets, inconspicuous, usually < 2 mm.

0 or 1–5+ linear to filiform bractlets, 2–3 mm.

Fruits

0.75–1.3 mm, sparsely hairy or glabrous.

1.5–2.5 mm, sparsely pubescent on ribs.

Heads

(10)20–60+.

12–24.

=40.

Senecio sylvaticus

Distribution

[WildflowerSearch map]

[BONAP county map]

Discussion

Disturbed areas, pastures, roadsides. Flowering May–Sep. 0–1600 m. Casc, CR, Est, Sisk, WV. CA, ID, WA; north to British Columbia, northeast to MT, northeastern North America; Europe. Exotic.

Senecio jacobea is an introduced weed, originally from Europe. It establishes in places with cool, wet summers and is particularly toxic to livestock. In most states where it occurs, this species has been declared a noxious weed.

Disturbed open wooded areas. Flowering May–Oct. 0–1200 m. Casc, CR, ECas, Est, Sisk, WV. CA, WA; north to British Columbia, scattered in eastern North America; Asia, Europe. Exotic.

Senecio sylvaticus is a native of Eurasia and favors cool, damp climates. In overall appearance, it resembles the more common S. vulgaris. However, the latter has distinctive black-tipped phyllaries, while S. sylvaticus has phyllaries that are generally green-tipped. This species is well established in the Pacific Northwest and in parts of eastern Canada. Elsewhere it is sporadic.

Source

Flora of Oregon, volume 2, page 340
Debra Trock

Flora of Oregon, volume 2, page 341
Debra Trock

Sibling taxa