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

alpine groundsel, showy alpine ragwort

Habit Perennials, (20–)50–120(–200) cm (caudices branched, ± woody). Perennials, (5–)10–60 cm (rhizomatous or with branched caudices).
Herbage

glabrous or sparsely floccose-tomentose when young.

(often purplish-tinged) glabrous or sparsely and unevenly hairy, especially near leaf axils and among heads, usually glabrescent.

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).

usually progressively reduced distally (basal sometimes smaller than proximal or mid leaves); petiolate (petioles shorter than to equaling blades, often clasping);

blades broadly lanceolate or lanceolate to oblanceolate, (5–)10–20+ × 2–4(–5+) cm, bases tapered, margins dentate to denticulate (distal leaves smaller, bractlike).

Ray florets

± 8;

corolla laminae 9–15 mm.

usually ± 13, sometimes fewer;

corolla laminae (10–)15–25 mm.

Phyllaries

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

± 13 or ± 21, tips often black or brownish (sometimes with scattered black hairs).

Calyculi

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

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

Heads

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

nodding, 1–5(–10).

Cypselae

glabrous.

glabrous.

2n

= 40, 80.

= 40, ca. 175–180.

Senecio triangularis

Senecio amplectens

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
CO; MT; NM; NV; 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.)

Varieties 2 (2 in the flora).

The varieties of Senecio amplectens are distinguished by morphologic tendencies and habitat preferences; there are many intermediates. Where the ranges of the two overlap, var. amplectens occurs at slightly lower elevations than var. holmii.

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

Key
1. Plants (30–)40–60+; herbage sometimes sparsely hairy; leaves mostly proximal and mid cauline; phyllaries frequently black or purplish toward tips, sometimes with black hairs on abaxial faces
var. amplectens
1. Plants (5–)10–20(–30) cm; herbage glabrous or glabrate at flowering; leaves mostly basal and proximal; phyllaries green or light purplish, glabrous
var. holmii
Source FNA vol. 20, p. 566. FNA vol. 20, p. 552.
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. 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. triangularis, S. viscosus, S. vulgaris, S. warnockii, S. wootonii
Subordinate taxa
S. amplectens var. amplectens, S. amplectens var. holmii
Synonyms S. gibbonsii, S. saliens, S. triangularis var. angustifolius Ligularia amplectens
Name authority Hooker: Fl. Bor.-Amer. 1: 332, plate 115. (1834) A. Gray: Amer. J. Sci. Arts, ser. 2, 33: 240. (1862)
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