Senecio flaccidus
Senecio hydrophiloides
Douglas' groundsel, Mono groundsel, shrubby butterweed, shrubby ragwort, threadleaf groundsel, threadleaf ragwort
stout meadow groundsel, sweet marsh ragwort, sweet-marsh butterweed, tall groundsel
glabrous or ± lanate-tomentose.
usually glabrous or glabrescent (young plants sparsely tomentose).
usually multiple (little branched, arching-erect).
usually single, sometimes 2–4 clustered (sometimes reddish-tinged).
± 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).
progressively reduced distally; usually petiolate (petioles often winged);
blades elliptic to broadly lanceolate, 5–15(–20) × 2–7 cm, bases broadly to narrowly tapered, margins dentate to denticulate (distal leaves sessile, bractlike).
usually ± 8 or ± 13, sometimes ± 21;
corolla laminae 10–15(–20) mm (mostly yellow, sometimes ochroleucous).
0 or (± 3 or 5) ± 8;
corolla laminae 5–10 mm.
± 13 or ± 21+, 5–10(–12) mm, tips green or minutely black.
(± 8) ± 13 (± 21), 4–9 mm, tips (minutely to prominently) black.
usually of 3–5+ bractlets (lengths often to 1/2+ phyllaries), sometimes 0.
of 2–5 bractlets (less than 2 mm).
(1–)3–10(–20+) in corymbiform or subcorymbiform clusters, often gathered in larger, showy arrays (involucres campanulate or cylindric).
(6–)15–30+ in congested or loose, corymbiform arrays.
hairy.
glabrous.
= 40.
= 40.
Senecio flaccidus
Senecio hydrophiloides
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.)
Plants of Senecio hydrophiloides from toward the western end of the range tend to have the heads more or less congested and eradiate and stems loosely clustered; plants from toward the eastern edge tend to have heads loosely arrayed and radiate and stems single. The two forms have been recognized as weakly defined species (or varieties), the former as Senecio foetidus and the latter as S. hydrophiloides. They intergrade so completely that they are best treated as a single, variable taxon. The use of the epithet foetidus for the broadly conceived single species was based on a bibliographic misunderstanding; the correct epithet is hydrophiloides (T. M. Barkley 1978; A. Cronquist 1994).
In 1900, Thomas Howell gave the name Senecio oreganus to a collection from Lake Labish, near Salem, Oregon. The area has seen much disturbance and development since Howell’s time, and the plant appears to be extinct in the region. The collection is difficult to exclude from S. hydrophiloides, and the collection is here regarded as an odd outlier of S. hydrophiloides, which is known chiefly from east of the Cascade uplift. Howell’s collection and therefore the name S. oreganus also have been treated within S. sphaerocephalus (T. M. Barkley 1978; A. Cronquist 1955); that attribution appears to be in error. The “type” materials are now in the herbarium of Oregon State University in Corvallis.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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 |
KS Wildflowers- 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
