Flora of North America species comparison

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Senecio rapifolius

Senecio jacobaea

openwoods ragwort

stinking willie, tansy ragwort
Habit Perennials, (20–)30–60 cm (rhizomes branched, spreading or suberect). Perennials, 20–80(–100) cm (taprooted or branched caudices surmounting taproots).
Herbage

(unevenly purple-tinged, often glaucous) glabrous.

sparsely and unevenly tomentose, glabrescent except in leaf axils and among heads.
Stems

1–(2–3).

(often purplish-tinged) usually single, sometimes loosely clustered.
Leaves

progressively reduced distally; petiolate;

blades ovate to oblanceolate, 4–8(–9+) × (2–)3–5 cm, bases tapered, margins dentate to incised-dentate (some denticles callous; mid leaves similar, smaller, ± clasping; distal leaves bractlike).

± 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

0.

± 13;

corolla laminae 8–12 mm.
Phyllaries

(± 5) ± 8, 3–4(–5) mm, tips green or brownish.

± 13, 3–4(–5) mm, tips black or greenish.
Calyculi

0 or of 1–3+ lance-deltate to lance-linear bractlets (mostly less than 1 mm).

of 2–6 (inconspicuous) bractlets (less than 2 mm).
Heads

25–60+ in cymiform clusters of 3–12.

(10–)20–60+ in corymbiform arrays.
Cypselae

glabrous.

all sparsely hairy or ray cypselae glabrous.
2n

= 40.

= 40.

Senecio rapifolius

Senecio jacobaea
Phenology Flowering late summer–early fall. Flowering spring–early summer(–fall).
Habitat Rocky hillsides and cliffs in coniferous wooded areas Disturbed sites, pastures, roadsides, and waste grounds
Elevation 1800–2800 m (5900–9200 ft) 0–1500 m (0–4900 ft)
Distribution
from FNA
CO; ID; SD; WY
[WildflowerSearch map]
[BONAP county map]
from FNA
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]
[WildflowerSearch map]
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. 553. FNA vol. 20, p. 568.
Parent taxa Asteraceae > tribe Senecioneae > Senecio Asteraceae > tribe Senecioneae > Senecio
Sibling taxa
S. actinella, S. amplectens, S. ampullaceus, S. aphanactis, S. arizonicus, S. aronicoides, S. astephanus, S. atratus, S. bigelovii, S. blochmaniae, S. californicus, S. cannabifolius, S. clarkianus, S. crassulus, S. elegans, S. elmeri, S. eremophilus, S. ertterae, S. erucifolius, S. flaccidus, S. fremontii, S. hydrophiloides, S. hydrophilus, S. integerrimus, S. jacobaea, S. lemmonii, S. lugens, S. lyonii, S. megacephalus, S. mohavensis, S. multidentatus, S. neowebsteri, S. parryi, S. pattersonensis, S. pseudoarnica, S. pudicus, S. quaylei, S. riddellii, S. sacramentanus, S. scorzonella, S. serra, S. sheldonensis, S. soldanella, S. spartioides, S. sphaerocephalus, S. spribillei, S. squalidus, S. sylvaticus, S. taraxacoides, S. triangularis, S. viscosus, S. vulgaris, S. warnockii, S. wootonii
S. actinella, S. amplectens, S. ampullaceus, S. aphanactis, S. arizonicus, S. aronicoides, S. astephanus, S. atratus, S. bigelovii, S. blochmaniae, S. californicus, S. cannabifolius, S. clarkianus, S. crassulus, S. elegans, S. elmeri, S. eremophilus, S. ertterae, S. erucifolius, S. flaccidus, S. fremontii, S. hydrophiloides, S. hydrophilus, S. integerrimus, S. lemmonii, S. lugens, S. lyonii, S. megacephalus, S. mohavensis, S. multidentatus, S. neowebsteri, S. parryi, S. pattersonensis, S. pseudoarnica, S. pudicus, S. quaylei, S. rapifolius, S. riddellii, S. sacramentanus, S. scorzonella, S. serra, S. sheldonensis, S. soldanella, S. spartioides, S. sphaerocephalus, S. spribillei, S. squalidus, S. sylvaticus, S. taraxacoides, S. triangularis, S. viscosus, S. vulgaris, S. warnockii, S. wootonii
Synonyms Jacobaea vulgaris
Name authority Nuttall: Trans. Amer. Philos. Soc., n. s. 7: 409. (1841) Linnaeus: Sp. Pl. 2: 870. (1753)
Web links 
Unless otherwise noted, all data comes from the online version of the Flora of North America, who have made most of their content available via a Creative Commons license (CC BY 4.0).



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