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

ball-head ragwort, marsh groundsel, mountain marsh butterweed

Habit Perennials, (20–)50–120(–200) cm (caudices branched, ± woody). Perennials, (30–)40–80 cm (rhizomes stout).
Herbage

glabrous or sparsely floccose-tomentose when young.

tomentose, unevenly glabrescent.

Stems

single or loosely clustered.

single.

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).

reduced distally; petiolate;

blades oblanceolate to elliptic, 4–12x 1–4 cm, bases tapered, margins weakly dentate or denticulate (denticles callous; mid leaves similar, smaller; distal leaves bractlike).

Ray florets

± 8;

corolla laminae 9–15 mm.

± 13;

corolla laminae 6–10 mm.

Phyllaries

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

(± 13) ± 21, 3–7 mm, tips black or brownish.

Calyculi

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

of 1–5 bractlets (longest 2–3 mm).

Heads

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

(3–)5–24 in corymbiform arrays.

Cypselae

glabrous.

usually hairy, sometimes glabrous.

2n

= 40, 80.

= 40.

Senecio triangularis

Senecio sphaerocephalus

Phenology Flowering summer. Flowering spring–early summer.
Habitat Damp places, open woodlands, especially rocky stream banks in coniferous forests Open meadows, especially in coniferous associations
Elevation 100–3300 m (300–10800 ft) 1000–1800 m (3300–5900 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
ID; MT; NV; OR; 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. 555.
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. 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. 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. altus, S. latus, S. lugens var. hookeri
Name authority Hooker: Fl. Bor.-Amer. 1: 332, plate 115. (1834) Greene: Pittonia 3: 106. (1896)
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