Senecio integerrimus |
Senecio jacobaea |
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lambstongue ragwort, western groundsel |
stinking willie, tansy ragwort |
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Habit | Herbs perennial or biennial, (1)2–7 dm; caudices button-like, with fleshy, fibrous, unbranched roots. | Herbs perennial, 2–8(10) dm; caudices ± woody, branching, rhizomatous. |
Stems | 1, loosely arachnoid-tomentose, or villous, glabrate with age. |
1, or rarely 2–4 and loosely clustered, often purple-tinged, sparsely and unevenly tomentose. |
Leaves | 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. |
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. |
Inflorescences | corymb-like arrays; bracts 0 or inconspicuous. |
compound corymb-like arrays; bracts conspicuous but small. |
Involucres | urn-shaped. |
widely cylindric or urn-shaped. |
Ray florets | 5, rarely 0; rays 6–15(20) mm, yellow or white to pale yellow. |
~13; rays 8–12 mm. |
Disc florets | 35–45. |
60–70+. |
Phyllaries | (8)13 or 21; tips usually black, sometimes green. |
13, 3–4(5); tips black or dark green. |
Calyculi | 1–5+, inconspicuous, usually < 2 mm. |
2–6 bractlets, inconspicuous, usually < 2 mm. |
Fruits | 2.5–3 mm, usually glabrous, sometimes hairy along ribs. |
0.75–1.3 mm, sparsely hairy or glabrous. |
Heads | 6–15(30+). |
(10)20–60+. |
2n | =40, 80. |
=40. |
Senecio integerrimus |
Senecio jacobaea |
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Distribution | ||
Discussion | Western North America. 5 varieties; 3 varieties treated in Flora. |
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. |
Source | Flora of Oregon, volume 2, page 339 Debra Trock |
Flora of Oregon, volume 2, page 340 Debra Trock |
Sibling taxa | ||
Subordinate taxa | ||
Synonyms | Jacobaea vulgaris | |
Web links |
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