Flora of North America species comparison

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Senecio triangularis

Senecio viscosus

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

stickly groundsel, sticky ragwort
Habit Perennials, (20–)50–120(–200) cm (caudices branched, ± woody). Annuals, (10–)20–40(–60) cm (taprooted).
Herbage

glabrous or sparsely floccose-tomentose when young.

densely fetid-viscid (hairs glandular).
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).

evenly distributed; petiolate;

blades obovate to oblong (pinnately dissected to pinnatifid), 2–7 × 1.5–4 cm, bases tapered or ± truncate, ultimate margins wavy or crenate-dentate (distal leaves sessile, smaller, ± clasping).
Ray florets

± 8;

corolla laminae 9–15 mm.

± 13;

corolla laminae 1–2 mm (usually coiled, scarcely surpassing phyllaries).
Phyllaries

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

(± 13) ± 21, 5–7 mm, tips black.
Calyculi

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

of 2–5 bractlets (largest to 4 mm).
Heads

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

(1–)3–8(–30) in irregular, corymbiform arrays.
Cypselae

glabrous.

usually glabrous, sometimes hairy.
2n

= 40, 80.

= 40.

Senecio triangularis

Senecio viscosus
Phenology Flowering summer. Flowering spring–fall.
Habitat Damp places, open woodlands, especially rocky stream banks in coniferous forests Disturbed sites, especially open sandy or gravelly places
Elevation 100–3300 m (300–10800 ft) 1–300 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
CT; IL; MA; ME; MN; NH; NJ; NY; PA; RI; WI; AB; BC; MB; NB; NF; NS; ON; PE; QC; SK; SPM; Eurasia [Introduced in North America]
[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.)

Senecio viscosus is a smelly, Eurasian weed now widely scattered in areas of cool damp climates, often as a casual waif. The viscid hairs trap wind-blown particles of sand, dust, and soot, which give the surfaces varying textures and colors.

(Discussion copyrighted by Flora of North America; reprinted with permission.)
Source FNA vol. 20, p. 566. FNA vol. 20, p. 562.
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. squalidus, S. sylvaticus, S. taraxacoides, S. triangularis, 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: 868. (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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