OregonFlora: Senecio triangularis vs. Senecio clarkianus

	Senecio triangularis	Senecio clarkianus
	arrowleaf groundsel
Habit	Herbs perennial, (2)5–12(20) dm; caudices branching, woody, rhizomatous.
Stems	1 or 2–4 and loosely clustered, glabrous or sparsely pubescent.
Leaves	basal present at flowering; cauline ± evenly distributed along stems, gradually reduced distally, narrowly to widely triangular, bases tapered to truncate or cordate; margins dentate, rarely subentire; surfaces sparsely tomentose to nearly glabrous; proximal petiolate; distal sessile.
Inflorescences	corymb- or ± raceme-like arrays; bracts conspicuous.
Involucres	cylindric to narrowly campanulate.
Ray florets	~8; rays 9–15 mm.
Disc florets	35–45.
Phyllaries	(8)13(21), 6–10 mm; tips green, rarely black.
Calyculi	2–6 bractlets, inconspicuous, rarely > 2 mm.
Fruits	2.5–3.5 mm, glabrous.
Heads	10–30(60).
2n	=40, 80.

	Senecio triangularis	Senecio clarkianus
Distribution	[WildflowerSearch map] [BONAP county map]	[WildflowerSearch map] [BONAP county map]
Discussion	Open areas, rocky streambanks, wet meadows, bogs, damp places in coniferous forests. Flowering May–Sep. 0–2800 m. BR, BW, Casc, CR, ECas, Est, Lava, Sisk, WV. CA, ID, NV, WA; north to AK, northeast to MT, east to WY, southeast to NM. Native. Some plants with narrow, subentire leaves that taper to the petioles have been found in acidic bogs in Washington and Oregon. A few authors recognize these as variety angustifolia. However, this author has observed several specimens (specifically indicated as being collected in bogs) that had both narrower leaves and the wider leaves more typical of variety triangularis on the same plant.
Source	Flora of Oregon, volume 2, page 341 Debra Trock
Sibling taxa	S. aronicoides, S. crassulus, S. ertterae, S. fremontii, S. hydrophiloides, S. hydrophilus, S. integerrimus, S. jacobaea, S. serra, S. sphaerocephalus, S. sylvaticus, S. viscosus, S. vulgaris	S. aronicoides, S. crassulus, S. ertterae, S. fremontii, S. hydrophiloides, S. hydrophilus, S. integerrimus, S. jacobaea, S. serra, S. sphaerocephalus, S. sylvaticus, S. triangularis, S. viscosus, S. vulgaris
Synonyms	Senecio gibbonsii, Senecio triangularis var. angustifolius, Senecio triangularis var. triangularis
Web links	Local floras: BC, CA, OR, WA Local Web sites: CalFlora, CalPhotos, Flora NW, PNW Herbaria, Turner Photog. WildflowerSearch iNaturalist (observations) USDA Plants Database LBJ Wildflower Center SEINet Plants of the World Online Encyclopedia of Life Wikipedia Google Image Search	Local floras: CA Local Web sites: CalFlora, CalPhotos, Flora NW, PNW Herbaria WildflowerSearch iNaturalist (observations) USDA Plants Database LBJ Wildflower Center SEINet Plants of the World Online Encyclopedia of Life Wikipedia Google Image Search

Senecio clarkianus

arrowleaf groundsel

Habit

Herbs perennial, (2)5–12(20) dm; caudices branching, woody, rhizomatous.

Stems

1 or 2–4 and loosely clustered, glabrous or sparsely pubescent.

Leaves

basal present at flowering;

cauline ± evenly distributed along stems, gradually reduced distally, narrowly to widely triangular, bases tapered to truncate or cordate;

margins dentate, rarely subentire;

surfaces sparsely tomentose to nearly glabrous;

proximal petiolate;

distal sessile.

Inflorescences

corymb- or ± raceme-like arrays;

bracts conspicuous.

Involucres

cylindric to narrowly campanulate.

Ray florets

~8;

rays 9–15 mm.

Disc florets

35–45.

Phyllaries

(8)13(21), 6–10 mm;

tips green, rarely black.

Calyculi

2–6 bractlets, inconspicuous, rarely > 2 mm.

Fruits

2.5–3.5 mm, glabrous.

Heads

10–30(60).

=40, 80.

Senecio clarkianus

Distribution

[WildflowerSearch map]

[BONAP county map]

[WildflowerSearch map]

[BONAP county map]

Discussion

Open areas, rocky streambanks, wet meadows, bogs, damp places in coniferous forests. Flowering May–Sep. 0–2800 m. BR, BW, Casc, CR, ECas, Est, Lava, Sisk, WV. CA, ID, NV, WA; north to AK, northeast to MT, east to WY, southeast to NM. Native.

Some plants with narrow, subentire leaves that taper to the petioles have been found in acidic bogs in Washington and Oregon. A few authors recognize these as variety angustifolia. However, this author has observed several specimens (specifically indicated as being collected in bogs) that had both narrower leaves and the wider leaves more typical of variety triangularis on the same plant.

Source

Flora of Oregon, volume 2, page 341
Debra Trock

Sibling taxa