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

tall blacktip ragwort

Habit Perennials, (20–)50–120(–200) cm (caudices branched, ± woody). Perennials, (20–)35–70(–80+) cm (rhizomes or caudices branched, erect to weakly creeping).
Herbage

glabrous or sparsely floccose-tomentose when young.

floccose-tomentose to canescent, sometimes unevenly glabrescent.

Stems

single or loosely clustered.

1–(2–5).

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;

blades oblong-ovate to oblanceolate, (5–)10–30 × 1.5–4(–6) cm, bases tapered, margins dentate (denticles, dark, callous; mid leaves similar, sessile, smaller; distal leaves bractlike).

Ray florets

± 8;

corolla laminae 9–15 mm.

(± 3) ± 5;

corolla laminae 5–8 mm.

Phyllaries

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

(± 5) ± 8, 6–8 mm, tips black.

Calyculi

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

of 2–5 linear bractlets (lengths to 1/3 phyllaries).

Heads

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

20–60+ in corymbiform or subpaniculiform arrays.

Cypselae

glabrous.

glabrous.

2n

= 40, 80.

= 40. (A report of 2n = 46 is presumably erroneous.)

Senecio triangularis

Senecio atratus

Phenology Flowering summer. Flowering late spring–early fall.
Habitat Damp places, open woodlands, especially rocky stream banks in coniferous forests Dry or drying, rocky or sandy sites in coniferous areas, especially sites with frequent disturbance
Elevation 100–3300 m (300–10800 ft) 2800–4000 m (9200–13100 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
CO; NM; UT; WY
[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.)

Source FNA vol. 20, p. 566. FNA vol. 20, p. 554.
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. 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. vulgaris, S. warnockii, S. wootonii
Synonyms S. gibbonsii, S. saliens, S. triangularis var. angustifolius S. atratus var. milleflorus, S. milleflorus
Name authority Hooker: Fl. Bor.-Amer. 1: 332, plate 115. (1834) Greene: Pittonia 3: 105. (1896)
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