Senecio jacobaea

Linnaeus

Sp. Pl. 2: 870. 1753.

Common names: Tansy ragwort stinking Willie
IntroducedIllustrated
Synonyms: Jacobaea vulgaris Gaertner
Treatment appears in FNA Volume 20. Treatment on page 568. Mentioned on page 546, 570.

Perennials, 20–80 (–100) cm (taprooted or branched caudices surmounting taproots). Herbage sparsely and unevenly tomentose, glabrescent except in leaf-axils and among heads. Stems (often purplish-tinged) usually single, sometimes loosely clustered. Leaves ± 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). Heads (10–) 20–60+ in corymbiform arrays. Calyculi of 2–6 (inconspicuous) bractlets (less than 2 mm). Phyllaries ± 13, 3–4 (–5) mm, tips black or greenish. Ray-florets ± 13; corolla laminae 8–12 mm. Cypselae all sparsely hairy or ray cypselae glabrous. 2n = 40.


Phenology: Flowering spring–early summer(–fall).
Habitat: Disturbed sites, pastures, roadsides, and waste grounds
Elevation: 0–1500 m

Distribution

V20-1279-distribution-map.gif

Introduced; St. Pierre and Miquelon, B.C., N.B., Nfld. and Labr. (Nfld.), N.S., Ont., P.E.I., Que., Calif., Idaho, Ill., Maine, Mass., Mich., Mont., N.J., N.Y., Oreg., Pa., Wash., Europe

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.

Selected References

None.

Lower Taxa

None.
... more about "Senecio jacobaea"
not tailed +, rounded +  and obtuse +
papillate +
truncate-penicillate +
scarious +
usually ovate +  and lance-linear +
indeterminate +  and determinate +
Theodore M. Barkley† +
Linnaeus +
tapered +
20 cm200 mm <br />0.2 m <br /> (30 cm300 mm <br />0.3 m <br />) +
5 cm50 mm <br />0.05 m <br /> (12 cm120 mm <br />0.12 m <br />) +
7 cm70 mm <br />0.07 m <br /> (20 cm200 mm <br />0.2 m <br />) +
ovate;broadly ovate +
2 cm20 mm <br />0.02 m <br /> (5 cm50 mm <br />0.05 m <br />) +
winged;nerved;ribbed +
barbellulate +  and smooth +
white +  and stramineous +
Tansy ragwort +  and stinking Willie +
purplish +, reddish +, white +, ochroleucous +, yellow +  and white rarely reddish +
0.8 cm8 mm <br />0.008 m <br /> (1.2 cm12 mm <br />0.012 m <br />) +
angled +, 5-ribbed +, prismatic +  and cylindric +
fertile +  and bisexual +
fertile +  and bisexual +
St. Pierre and Miquelon +, B.C. +, N.B. +, Nfld. and Labr. (Nfld.) +, N.S. +, Ont. +, P.E.I. +, Que. +, Calif. +, Idaho +, Ill. +, Maine +, Mass. +, Mich. +, Mont. +, N.J. +, N.Y. +, Oreg. +, Pa. +, Wash. +  and Europe +
0–1500 m +
hairy +  and glabrous +
pistillate +, staminate +  and neuter +
winged +  and beaked +
dispersed +
Disturbed sites, pastures, roadsides, and waste grounds +
discoid +  and radiate +
indeterminate +
heterogamous +  and homogamous +
glabrescent +  and tomentose +
each +  and sessile +
0.5 cm5 mm <br />0.005 m <br /> (1.5 cm15 mm <br />0.015 m <br />) +
turbinate;campanulate +
distributed +
cauline +  and basal +
erect;recurved +
deltate +
dentate to pinnatifid +  and entire +
2-carpellate +
persistent +
Flowering spring–early summer(–fall). +
0.4 cm4 mm <br />0.004 m <br /> (0.5 cm5 mm <br />0.005 m <br />) +
mostly oblong +  and lanceolate or linear +
0.3 cm3 mm <br />0.003 m <br /> (0.4 cm4 mm <br />0.004 m <br />) +
bearing subulate enations +, hairy +  and bristly +
flat;convex +
exalbuminous +
Introduced +  and Illustrated +
appendaged +  and truncate +
papillate +
Jacobaea vulgaris +
Senecio jacobaea +
species +
campanulate +
greenish +  and black +
denticulate +  and serrate or toothed +
80 cm800 mm <br />0.8 m <br /> (100 cm1,000 mm <br />1 m <br />) +
20 cm200 mm <br />0.2 m <br /> (80 cm800 mm <br />0.8 m <br />) +
100 cm1,000 mm <br />1 m <br /> (250 cm2,500 mm <br />2.5 m <br />) +
shrub +  and subshrub +