Flora of North America species comparison

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Senecio sylvaticus

Senecio riddellii

heath groundsel, wood groundsel, woodland groundsel, woodland ragwort

Riddell's groundsel, Riddell's ragwort
Habit Annuals, (15–)30–80+ cm (taproots fibrous-rooted). Subshrubs, 30–100 cm (taproots forming woody crowns).
Herbage

puberulent (hairs abundant, curly).

glabrous.
Stems

single.

usually multiple (branching upward).
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 (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 or 1–8+;

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

± 8;

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

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

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

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

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

12–24 in corymbiform arrays.

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

hairy (especially on angles).

hirtellous.
2n

= 40.

= 40.

Senecio sylvaticus

Senecio riddellii
Phenology Flowering late spring–summer (northern areas of cool, climate); winter (southern areas). Flowering mostly mid summer–fall, occasionally spring.
Habitat Mildly disturbed woodlands, open, sandy sites Sandy or rocky open sites, especially drying, open, flood plains
Elevation 100–300 m (300–1000 ft) 600–2500 m (2000–8200 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
AZ; CO; KS; NE; NM; OK; SD; TX; WY
[WildflowerSearch map]
[BONAP county 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 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. 563. 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. 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. 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: 868. (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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