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

hoary ragwort

Habit Perennials, (20–)50–120(–200) cm (caudices branched, ± woody). Perennials, 30–120 cm (rhizomes branched, sometimes producing stolons).
Herbage

glabrous or sparsely floccose-tomentose when young.

floccose-tomentose, unevenly glabrescent (persistently hairy on abaxial leaf faces).

Stems

single or loosely clustered.

usually single, sometimes 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).

± evenly distributed (basal and proximal sometimes withering before flowering); petiolate (proximal) or sessile;

blades ovoid or oblong to spatulate (usually pinnatifid to pinnatisect, lobes ± lanceolate to linear), (3–)5–12 × (1.5–)2–4 cm, bases tapered to ± truncate, ultimate margins (often revolute) dentate or entire.

Ray florets

± 8;

corolla laminae 9–15 mm.

± 13;

corolla laminae 12–15 mm.

Phyllaries

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

± 13, 5–7 mm, tips green or greenish.

Calyculi

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

of 4–6(–10) bractlets (lengths to 1/2 phyllaries).

Heads

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

20–60 in corymbiform arrays.

Cypselae

glabrous.

hairy.

2n

= 40, 80.

Senecio triangularis

Senecio erucifolius

Phenology Flowering summer. Flowering summer.
Habitat Damp places, open woodlands, especially rocky stream banks in coniferous forests Waste grounds
Elevation 100–3300 m (300–10800 ft) 0–200+ m (0–700+ 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
PA; Old World [Introduced in North America]
[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.)

Senecio erucifolius has been introduced occasionally around seaports and has persisted. At present, it appears to be uncommon and highly localized; it should be expected almost any place that its close relative, Senecio jacobaea, occurs.

Senecio erucifolius was treated in Jacobaea by E. Wiebe (2000); see discussion under 53. S. jacobaea.

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

Source FNA vol. 20, p. 566. FNA vol. 20, p. 569.
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. bigelovii, S. blochmaniae, S. californicus, S. cannabifolius, S. clarkianus, S. crassulus, S. elegans, S. elmeri, S. eremophilus, S. ertterae, 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
Synonyms S. gibbonsii, S. saliens, S. triangularis var. angustifolius Jacobaea erucifolia
Name authority Hooker: Fl. Bor.-Amer. 1: 332, plate 115. (1834) Linnaeus: Fl. Suec. ed. 2, 291. (1755)
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