Flora of North America species comparison

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Senecio sylvaticus

Senecio jacobaea

heath groundsel, wood groundsel, woodland groundsel, woodland ragwort

stinking willie, tansy ragwort
Habit Annuals, (15–)30–80+ cm (taproots fibrous-rooted). Perennials, 20–80(–100) cm (taprooted or branched caudices surmounting taproots).
Herbage

puberulent (hairs abundant, curly).

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

single.

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

evenly distributed; petiolate;

blades obovate to oblong, 3–7(–12) × 1–3(–4) cm, usually 1–2-pinnate, bases tapered, ultimate margins dentate (distal leaves similar, clasping, 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 or 1–8+;

corolla laminae usually 1–2+ mm (barely surpassing phyllaries).

± 13;

corolla laminae 8–12 mm.
Phyllaries

± 13 (± 21), 4–7+ mm, tips greenish or minutely black.

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

0 or of 1–5+ linear to filiform bractlets.

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

12–24 in corymbiform arrays.

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

hairy (especially on angles).

all sparsely hairy or ray cypselae glabrous.
2n

= 40.

= 40.

Senecio sylvaticus

Senecio jacobaea
Phenology Flowering late spring–summer (northern areas of cool, climate); winter (southern areas). Flowering spring–early summer(–fall).
Habitat Mildly disturbed woodlands, open, sandy sites Disturbed sites, pastures, roadsides, and waste grounds
Elevation 100–300 m (300–1000 ft) 0–1500 m (0–4900 ft)
Distribution
from FNA
CA; LA; MA; MI; NJ; OH; OR; PA; WA; WI; BC; NB; NF; NS; PE; QC; Eurasia [Introduced in North America]
[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 sylvaticus is a Eurasian weed that favors cool, wet climates. It is well established in coastal areas of the Pacific Coast and in parts of Newfoundland and Quebec; elsewhere in the flora, it appears to be sporadic.

(Discussion copyrighted by Flora of North America; reprinted with permission.)

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. 563. 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. rapifolius, S. riddellii, S. sacramentanus, S. scorzonella, S. serra, S. sheldonensis, S. soldanella, S. spartioides, S. sphaerocephalus, S. spribillei, S. squalidus, 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 Linnaeus: Sp. Pl. 2: 868. (1753) 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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