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Mono ragwort, Mount Patterson senecio

Riddell's groundsel, Riddell's ragwort

Habit Perennials, to 10 cm (rhizomes branching). Subshrubs, 30–100 cm (taproots forming woody crowns).
Herbage

(sometimes reddish-tinged, especially proximally) glabrous.

glabrous.

Stems

1–3 (arching upward).

usually multiple (branching upward).

Leaves

evenly distributed (proximal often withering before flowering); obscurely petiolate or sessile;

blades oblanceolate to lance-linear (sometimes with 1–2 lateral lobes), 2–4 cm × 3–5 mm, bases subdecurrent, weakly clasping, margins entire or wavy (often revolute).

± 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

± 8;

corolla laminae 5–10 mm.

± 8;

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

Phyllaries

± 13, 5–7(–8) mm.

± 13, 7–10(–12+) mm, tips green.

Calyculi

of 3–5+ (inconspicuous) bractlets.

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

Heads

1(–4).

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

Cypselae

glabrous.

hirtellous.

2n

= 40.

Senecio pattersonensis

Senecio riddellii

Phenology Flowering summer. Flowering mostly mid summer–fall, occasionally spring.
Habitat Talus slopes Sandy or rocky open sites, especially drying, open, flood plains
Elevation 3000–3700 m (9800–12100 ft) 600–2500 m (2000–8200 ft)
Distribution
from FNA
CA; NV
[BONAP county map]
from FNA
AZ; CO; KS; NE; NM; OK; SD; TX; WY
[WildflowerSearch map]
[BONAP county map]
Discussion

Of conservation concern.

Senecio pattersonensis has the aspect of a depauperate S. fremontii with notably narrow leaves. Some plants in collections appear to be intergrades with S. spartioides.

(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. 564. 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. 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
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. revolutus S. filifolius var. fremontii, S. riddellii var. parksii, S. spartioides var. fremontii, S. spartioides var. parksii, S. spartioides var. riddellii
Name authority Hoover: Leafl. W. Bot. 5: 60. (1947) Torrey & A. Gray: Fl. N. Amer. 2: 444. (1843)
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