Flora of North America species comparison

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Senecio vulgaris

Senecio riddellii

common groundsel, common ragwort, old-man-in-the-spring

Riddell's groundsel, Riddell's ragwort
Habit Annuals, (10–)20–50(–60+) cm (taprooted). Subshrubs, 30–100 cm (taproots forming woody crowns).
Herbage

glabrous or sparsely and unevenly tomentose when young.

glabrous.
Stems

usually 1.

usually multiple (branching upward).
Leaves

evenly distributed; petiolate;

blades ovate to oblanceolate, 2–10 × 0.5–2(–4) cm, bases tapered, margins lobulate to dentate, ultimate margins often secondarily dentate to denticulate (distal leaves sessile).

± evenly distributed (proximal often withering before flowering, pendulous);

sessile or obscurely petiolate;

blades linear-filiform (or irregularly pinnately divided into linear-filiform lobes), blades or lobes 4–9 cm × 1–5 mm, bases ± linear, ultimate margins entire.
Ray florets

0.

± 8;

corolla laminae (often falling early) 8–10 mm.
Phyllaries

± 21, 4–6 mm, tips usually green, sometimes black.

± 13, 7–10(–12+) mm, tips green.
Calyculi

of 2–4(–6+) bractlets (prominent, black-tipped, lengths about 1/4 phyllaries).

usually of 3–8+ lance-linear to filiform bractlets (lengths 1/10–1/3 phyllaries).
Heads

8–20 in loose, corymbiform arrays.

5–20+ in close, corymbiform arrays (involucres campanulate, 7–10 mm diam.).
Cypselae

usually sparsely hairy, sometimes nearly glabrous.

hirtellous.
2n

= 40.

= 40.

Senecio vulgaris

Senecio riddellii
Phenology Flowering early spring (through summer in far North). Flowering mostly mid summer–fall, occasionally spring.
Habitat Disturbed sites Sandy or rocky open sites, especially drying, open, flood plains
Elevation 1–1000 m (0–3300 ft) 600–2500 m (2000–8200 ft)
Distribution
from FNA
AK; AL; AZ; CA; CO; CT; DC; DE; FL; GA; IA; ID; IL; IN; KS; KY; LA; MA; MD; ME; MI; MN; MO; MS; MT; NC; ND; NE; NH; NJ; NV; OH; OK; OR; PA; RI; SC; SD; TN; TX; UT; VA; VT; WA; WI; WV; WY; AB; BC; MB; NB; NL; NS; NT; NU; ON; PE; QC; SK; YT; SPM; Greenland; Eurasia [Probably introduced]
[WildflowerSearch map]
[BONAP county map]
from FNA
AZ; CO; KS; NE; NM; OK; SD; TX; WY
[WildflowerSearch map]
[BONAP county map]
Discussion

Senecio vulgaris has not been collected in the Canadian Arctic north of Hudson Bay.

A widely scattered weed of Eurasian origin, Senecio vulgaris is particularly abundant in southern areas of cool damp winters or northern areas of cool damp summers.

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

Senecio riddellii intergrades morphologically with S. spartioides. Typically, the former has larger heads with campanulate involucres 7–10 mm diam.; the latter has cylindric involucres rarely more than 6 mm diam.

Senecio riddellii is poisonous to livestock. It is now locally scarce because of efforts to eradicate it.

(Discussion copyrighted by Flora of North America; reprinted with permission.)
Source FNA vol. 20, p. 562. FNA vol. 20, p. 560.
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. sylvaticus, S. taraxacoides, S. triangularis, S. viscosus, 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. 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. 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 S. filifolius var. fremontii, S. riddellii var. parksii, S. spartioides var. fremontii, S. spartioides var. parksii, S. spartioides var. riddellii
Name authority Linnaeus: Sp. Pl. 2: 867. (1753) Torrey & A. Gray: Fl. N. Amer. 2: 444. (1843)
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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