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Douglas' groundsel, Mono groundsel, shrubby butterweed, shrubby ragwort, threadleaf groundsel, threadleaf ragwort

heath groundsel, wood groundsel, woodland groundsel, woodland ragwort

Habit Subshrubs or shrubs, (30–)40–120+ cm (taproots forming woody crowns). Annuals, (15–)30–80+ cm (taproots fibrous-rooted).
Herbage

glabrous or ± lanate-tomentose.

puberulent (hairs abundant, curly).

Stems

usually multiple (little branched, arching-erect).

single.

Leaves

± evenly distributed;

sessile or obscurely petiolate;

blades narrowly linear to filiform (or pinnatifid, the segments linear to filiform), 3–10(–12) cm, bases ± linear, ultimate margins entire or remotely toothed (fascicles of smaller leaves sometimes borne in axils of larger leaves).

evenly distributed; petiolate;

blades obovate to oblong, 3–7(–12) × 1–3(–4) cm, usually 1–2-pinnate, bases tapered, ultimate margins dentate (distal leaves similar, clasping, bractlike).

Ray florets

usually ± 8 or ± 13, sometimes ± 21;

corolla laminae 10–15(–20) mm (mostly yellow, sometimes ochroleucous).

0 or 1–8+;

corolla laminae usually 1–2+ mm (barely surpassing phyllaries).

Phyllaries

± 13 or ± 21+, 5–10(–12) mm, tips green or minutely black.

± 13 (± 21), 4–7+ mm, tips greenish or minutely black.

Calyculi

usually of 3–5+ bractlets (lengths often to 1/2+ phyllaries), sometimes 0.

0 or of 1–5+ linear to filiform bractlets.

Heads

(1–)3–10(–20+) in corymbiform or subcorymbiform clusters, often gathered in larger, showy arrays (involucres campanulate or cylindric).

12–24 in corymbiform arrays.

Cypselae

hairy.

hairy (especially on angles).

2n

= 40.

= 40.

Senecio flaccidus

Senecio sylvaticus

Phenology Flowering late spring–summer (northern areas of cool, climate); winter (southern areas).
Habitat Mildly disturbed woodlands, open, sandy sites
Elevation 100–300 m (300–1000 ft)
Distribution
from FNA
AZ; CA; CO; KS; NM; NV; OK; TX; UT; Mexico
[WildflowerSearch map]
[BONAP county map]
from FNA
CA; LA; MA; MI; NJ; OH; OR; PA; WA; WI; BC; NB; NF; NS; PE; QC; Eurasia [Introduced in North America]
[WildflowerSearch map]
[BONAP county map]
Discussion

Varieties 3 (3 in the flora).

The varieties of Senecio flaccidus are distinguished by morphologic tendencies and geography. The species occurs southward to central Mexico; a sound understanding of the infraspecific taxonomy must await revisionary studies that include the Mexican plants.

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

Senecio sylvaticus is a Eurasian weed that favors cool, wet climates. It is well established in coastal areas of the Pacific Coast and in parts of Newfoundland and Quebec; elsewhere in the flora, it appears to be sporadic.

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

Key
1. Herbage usually tomentose (hairs whitish), sometimes unevenly glabrescent; bractlets of calyculi minute or 0; involucres cylindric or ± campanulate; phyllaries ± 13 or ± 21, 5–8+ mm
var. flaccidus
1. Herbage ± tomentose, glabrate, or glabrous; bractlets of calyculi well developed (lengths mostly 1/3 – 1/2 phyllaries); involucres ± campanulate; phyllaries ± 21, 7–12 mm
→ 2
2. Plants usually ± tomentose (usually with persistent, uneven grayish tomentum), sometimes unevenly glabrescent; California w of crests of Sierra Nevada and related ranges
var. douglasii
2. Plants glabrate or glabrous; California deserts e of crest of Sierra Nevada and eastward
var. monoensis
Source FNA vol. 20, p. 558. FNA vol. 20, p. 563.
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. 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
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. taraxacoides, S. triangularis, S. viscosus, S. vulgaris, S. warnockii, S. wootonii
Subordinate taxa
S. flaccidus var. douglasii, S. flaccidus var. flaccidus, S. flaccidus var. monoensis
Name authority Lessing: Linnaea 5: 161. (1830) Linnaeus: Sp. Pl. 2: 868. (1753)
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