Flora of North America species comparison

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Senecio triangularis

Senecio squalidus

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

oxford ragwort
Habit Perennials, (20–)50–120(–200) cm (caudices branched, ± woody). Annuals (or perennials), 15–60+ cm (taprooted).
Herbage

glabrous or sparsely floccose-tomentose when young.

sparsely, unevenly floccose to subglabrous, glabrescent.
Stems

single or loosely clustered.

single (branching distally).
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; petiolate (proximal, petioles ± winged);

blades obovate to oblong, 4–10 × 2–4+ cm, mostly lyrate-pinnatifid to pinnate, bases tapered, ultimate margins dentate (distal leaves similar, smaller, sessile).
Ray florets

± 8;

corolla laminae 9–15 mm.

± 13;

corolla laminae 5–8 mm.
Phyllaries

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

(± 13) ± 21, 5–6+ mm, tips black.
Calyculi

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

of 4–10+ bractlets (1–2+ mm).
Heads

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

(3–)6–20 in open, cymiform arrays.
Cypselae

glabrous.

usually hairy.
2n

= 40, 80.

= 20.

Senecio triangularis

Senecio squalidus
Phenology Flowering summer. Flowering late winter–spring or fall.
Habitat Damp places, open woodlands, especially rocky stream banks in coniferous forests Disturbed sites (in regions of cool, damp climates)
Elevation 100–3300 m (300–10800 ft) 0–300 m (0–1000 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
CA; NS; Europe [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 squalidus is native in Europe, where it is a common weed. It is apparently established in the San Francisco Bay area, California and has been reported from British Columbia, New Brunswick, and Nova Scotia. It is to be expected elsewhere.

(Discussion copyrighted by Flora of North America; reprinted with permission.)
Source FNA vol. 20, p. 566. FNA vol. 20, p. 560.
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. sphaerocephalus, S. spribillei, S. sylvaticus, S. taraxacoides, S. triangularis, S. viscosus, S. vulgaris, S. warnockii, S. wootonii
Synonyms S. gibbonsii, S. saliens, S. triangularis var. angustifolius
Name authority Hooker: Fl. Bor.-Amer. 1: 332, plate 115. (1834) Linnaeus: Sp. Pl. 2: 869. (1753)
Web links 
Unless otherwise noted, all data comes from the online version of the Flora of North America, who have made most of their content available via a Creative Commons license (CC BY 4.0).



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