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arrow-leaf groundsel, arrow-leaf ragwort, arrowleaf butterweed, groundsel

nodding groundsel, nodding ragwort

Habit Perennials, (20–)50–120(–200) cm (caudices branched, ± woody). Perennials, (20–)40–80(–120) cm (caudices fibrous-rooted).
Herbage

glabrous or sparsely floccose-tomentose when young.

usually floccose-tomentose to glabrescent, sometimes glabrous.

Stems

single or loosely clustered.

single or loosely clustered.

Leaves

evenly distributed; petiolate;

blades narrowly triangular, (3–)4–10+ × 2–6 cm, bases usually ± truncate, sometimes tapered, margins usually dentate, rarely subentire (distal leaves subsessile, smaller).

progressively reduced distally; petiolate (proximal);

blades ovate to lanceolate, 7–15 × (1–)2–5 cm, bases contracted or tapered, margins subentire or serrate to dentate (mid and distal leaves similar, sessile, bractlike, often clasping).

Ray florets

± 8;

corolla laminae 9–15 mm.

0.

Phyllaries

(± 8) ± 13 (± 21), 6–10 mm, tips usually green, rarely black.

± 13 or ± 21, 6–12 mm, tips green.

Calyculi

of 2–6 bractlets (rarely more than 2 mm).

of 4–10 linear bractlets (lengths mostly 1/3–1/2 phyllaries, sometimes 1 or 2 equaling phyllaries).

Heads

10–30(–60) in corymbiform to subracemiform arrays.

nodding (especially when young), (1–)3–12(–20) in racemiform or paniculiform arrays (terminal heads often largest).

Cypselae

glabrous.

glabrous.

2n

= 40, 80.

= 40.

Senecio triangularis

Senecio bigelovii

Phenology Flowering summer.
Habitat Damp places, open woodlands, especially rocky stream banks in coniferous forests
Elevation 100–3300 m (300–10800 ft)
Distribution
from FNA
AK; AZ; CA; CO; ID; MT; NM; NV; OR; WA; WY; AB; BC; NT; YT; PH
[WildflowerSearch map]
[BONAP county map]
from FNA
AZ; CO; NM; UT; WY; s Rocky Mountains and adjacent areas of the United States
[WildflowerSearch map]
[BONAP county map]
Discussion

Plants of Senecio triangularis with narrow, subentire leaves that taper to the petioles are occasionally encountered in acid bogs in Oregon and Washington and less frequently elsewhere. They are regarded as edaphic variants; they have been recognized as var. angustifolius.

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

Varieties 2 (2 in the flora).

The two varieties of Senecio bigelovii are distinguished by morphologic tendencies and by geography.

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

Key
1. Herbage glabrous or nearly so (at flowering); blades of proximal leaves often abruptly contracted or at least obtuse at bases; mid and distal leaves clasping; phyllaries mostly 13, 6–8+ mm
var. bigelovii
1. Herbage often floccose-tomentose, especially among heads and on abaxial faces of leaves; blades of proximal leaves usually tapered to petioles; mid and distal leaves weakly, if at all, clasping; phyllaries mostly 21, (7–)8–12 mm
var. hallii
Source FNA vol. 20, p. 566. FNA vol. 20, p. 549.
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. viscosus, S. vulgaris, S. warnockii, S. wootonii
S. actinella, S. amplectens, S. ampullaceus, S. aphanactis, S. arizonicus, S. aronicoides, S. astephanus, S. atratus, 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. vulgaris, S. warnockii, S. wootonii
Subordinate taxa
S. bigelovii var. bigelovii, S. bigelovii var. hallii
Synonyms S. gibbonsii, S. saliens, S. triangularis var. angustifolius Ligularia bigelovii
Name authority Hooker: Fl. Bor.-Amer. 1: 332, plate 115. (1834) A. Gray: in War Department [U.S.], Pacif. Railr. Rep. 4(5): 111. (1857)
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