Senecio hydrophiloides |
Senecio riddellii |
|
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stout meadow groundsel, sweet marsh ragwort, sweet-marsh butterweed, tall groundsel |
Riddell's groundsel, Riddell's ragwort |
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Habit | Perennials (biennials?), 30–100(–140) cm (caudices erect, roots fleshy-fibrous). | Subshrubs, 30–100 cm (taproots forming woody crowns). |
Herbage | usually glabrous or glabrescent (young plants sparsely tomentose). |
glabrous. |
Stems | usually single, sometimes 2–4 clustered (sometimes reddish-tinged). |
usually multiple (branching upward). |
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). |
± evenly distributed (proximal often withering before flowering, pendulous); sessile or obscurely petiolate; blades linear-filiform (or irregularly pinnately divided into linear-filiform lobes), blades or lobes 4–9 cm × 1–5 mm, bases ± linear, ultimate margins entire. |
Ray florets | 0 or (± 3 or 5) ± 8; corolla laminae 5–10 mm. |
± 8; corolla laminae (often falling early) 8–10 mm. |
Phyllaries | (± 8) ± 13 (± 21), 4–9 mm, tips (minutely to prominently) black. |
± 13, 7–10(–12+) mm, tips green. |
Calyculi | of 2–5 bractlets (less than 2 mm). |
usually of 3–8+ lance-linear to filiform bractlets (lengths 1/10–1/3 phyllaries). |
Heads | (6–)15–30+ in congested or loose, corymbiform arrays. |
5–20+ in close, corymbiform arrays (involucres campanulate, 7–10 mm diam.). |
Cypselae | glabrous. |
hirtellous. |
2n | = 40. |
= 40. |
Senecio hydrophiloides |
Senecio riddellii |
|
Phenology | Flowering spring–early summer. | Flowering mostly mid summer–fall, occasionally spring. |
Habitat | Damp hillsides, non-alkaline meadows, seepage sites | Sandy or rocky open sites, especially drying, open, flood plains |
Elevation | 1200–2200 m (3900–7200 ft) | 600–2500 m (2000–8200 ft) |
Distribution |
CA; ID; MT; NV; OR; UT; WA; WY; AB; BC
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AZ; CO; KS; NE; NM; OK; SD; TX; WY
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Discussion | 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.) |
Senecio riddellii intergrades morphologically with S. spartioides. Typically, the former has larger heads with campanulate involucres 7–10 mm diam.; the latter has cylindric involucres rarely more than 6 mm diam. Senecio riddellii is poisonous to livestock. It is now locally scarce because of efforts to eradicate it. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 20, p. 558. | FNA vol. 20, p. 560. |
Parent taxa | Asteraceae > tribe Senecioneae > Senecio | Asteraceae > tribe Senecioneae > Senecio |
Sibling taxa | ||
Synonyms | S. foetidus, S. foetidus var. hydrophiloides, S. oreganus | S. filifolius var. fremontii, S. riddellii var. parksii, S. spartioides var. fremontii, S. spartioides var. parksii, S. spartioides var. riddellii |
Name authority | Rydberg: Mem. New York Bot. Gard. 1: 441. (1900) | Torrey & A. Gray: Fl. N. Amer. 2: 444. (1843) |
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