Senecio jacobaea |
Senecio integerrimus |
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stinking willie, tansy ragwort |
lambstongue ragwort, western groundsel |
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Habit | Herbs perennial, 2–8(10) dm; caudices ± woody, branching, rhizomatous. | Herbs perennial or biennial, (1)2–7 dm; caudices button-like, with fleshy, fibrous, unbranched roots. |
Stems | 1, or rarely 2–4 and loosely clustered, often purple-tinged, sparsely and unevenly tomentose. |
1, loosely arachnoid-tomentose, or villous, glabrate with age. |
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. |
mostly basal; cauline progressively reduced distally; ± petiolate; basal and lower cauline elliptic, lanceolate, linear, oblanceolate, rounded-deltate, rarely suborbiculate, bases tapered or truncate to cordate; margins entire or dentate; distal becoming sessile 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. |
urn-shaped. |
Ray florets | ~13; rays 8–12 mm. |
5, rarely 0; rays 6–15(20) mm, yellow or white to pale yellow. |
Disc florets | 60–70+. |
35–45. |
Phyllaries | 13, 3–4(5); tips black or dark green. |
(8)13 or 21; tips usually black, sometimes green. |
Calyculi | 2–6 bractlets, inconspicuous, usually < 2 mm. |
1–5+, inconspicuous, usually < 2 mm. |
Fruits | 0.75–1.3 mm, sparsely hairy or glabrous. |
2.5–3 mm, usually glabrous, sometimes hairy along ribs. |
Heads | (10)20–60+. |
6–15(30+). |
2n | =40. |
=40, 80. |
Senecio jacobaea |
Senecio integerrimus |
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Distribution | ||
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. |
Western North America. 5 varieties; 3 varieties treated in Flora. |
Source | Flora of Oregon, volume 2, page 340 Debra Trock |
Flora of Oregon, volume 2, page 339 Debra Trock |
Sibling taxa | ||
Subordinate taxa | ||
Synonyms | Jacobaea vulgaris | |
Web links |
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