Senecio crassulus |
Senecio jacobaea |
|
---|---|---|
mountain meadow butterweed, thick-leaf groundsel, thick-leaf ragwort |
stinking willie, tansy ragwort |
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Habit | Perennials, (15–)20–50(–70) cm (rhizomes branched, ± woody). | Perennials, 20–80(–100) cm (taprooted or branched caudices surmounting taproots). |
Herbage | glabrous. |
sparsely and unevenly tomentose, glabrescent except in leaf axils and among heads. |
Stems | 1–(2–4). |
(often purplish-tinged) usually single, sometimes loosely clustered. |
Leaves | (thickish-turgid) progressively reduced distally; petiolate; blades broadly lanceolate to subelliptic, 2.5–15 × 1–5 cm, bases tapered, margins sharply dentate to subentire (some teeth callous; mid leaves sometimes larger than proximal; distal leaves sessile, smaller, often clasping). |
± 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). |
Ray florets | ± 8 or ± 13; corolla laminae 5–12 mm. |
± 13; corolla laminae 8–12 mm. |
Phyllaries | (± 8) ± 13 or ± 21, 5–9 mm, tips black (villous). |
± 13, 3–4(–5) mm, tips black or greenish. |
Calyculi | of (1–)3–6 linear to filiform bractlets (lengths to 1/3 phyllaries). |
of 2–6 (inconspicuous) bractlets (less than 2 mm). |
Heads | (1–)4–12 in corymbiform arrays. |
(10–)20–60+ in corymbiform arrays. |
Cypselae | glabrous. |
all sparsely hairy or ray cypselae glabrous. |
2n | = 40. |
= 40. |
Senecio crassulus |
Senecio jacobaea |
|
Phenology | Flowering summer. | Flowering spring–early summer(–fall). |
Habitat | Moist to drying hillsides, meadows, other open places in forest associations | Disturbed sites, pastures, roadsides, and waste grounds |
Elevation | 2200–3700 m (7200–12100 ft) | 0–1500 m (0–4900 ft) |
Distribution |
CO; ID; MT; NM; NV; OR; SD; UT; WY
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CA; ID; IL; MA; ME; MI; MT; NJ; NY; OR; PA; WA; BC; NB; NF; NS; ON; PE; QC; SPM; Europe [Introduced in North America]
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Discussion | 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.) |
|
Source | FNA vol. 20, p. 551. | FNA vol. 20, p. 568. |
Parent taxa | Asteraceae > tribe Senecioneae > Senecio | Asteraceae > tribe Senecioneae > Senecio |
Sibling taxa | ||
Synonyms | S. lapathifolius, S. semiamplexicaulis | Jacobaea vulgaris |
Name authority | A. Gray: Proc. Amer. Acad. Arts 19: 54. (1883) | Linnaeus: Sp. Pl. 2: 870. (1753) |
Web links |
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