Senecio sylvaticus |
Senecio hydrophiloides |
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heath groundsel, wood groundsel, woodland groundsel, woodland ragwort |
stout meadow groundsel, sweet marsh ragwort, sweet-marsh butterweed, tall groundsel |
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Habit | Annuals, (15–)30–80+ cm (taproots fibrous-rooted). | Perennials (biennials?), 30–100(–140) cm (caudices erect, roots fleshy-fibrous). |
Herbage | puberulent (hairs abundant, curly). |
usually glabrous or glabrescent (young plants sparsely tomentose). |
Stems | single. |
usually single, sometimes 2–4 clustered (sometimes reddish-tinged). |
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). |
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). |
Ray florets | 0 or 1–8+; corolla laminae usually 1–2+ mm (barely surpassing phyllaries). |
0 or (± 3 or 5) ± 8; corolla laminae 5–10 mm. |
Phyllaries | ± 13 (± 21), 4–7+ mm, tips greenish or minutely black. |
(± 8) ± 13 (± 21), 4–9 mm, tips (minutely to prominently) black. |
Calyculi | 0 or of 1–5+ linear to filiform bractlets. |
of 2–5 bractlets (less than 2 mm). |
Heads | 12–24 in corymbiform arrays. |
(6–)15–30+ in congested or loose, corymbiform arrays. |
Cypselae | hairy (especially on angles). |
glabrous. |
2n | = 40. |
= 40. |
Senecio sylvaticus |
Senecio hydrophiloides |
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Phenology | Flowering late spring–summer (northern areas of cool, climate); winter (southern areas). | Flowering spring–early summer. |
Habitat | Mildly disturbed woodlands, open, sandy sites | Damp hillsides, non-alkaline meadows, seepage sites |
Elevation | 100–300 m (300–1000 ft) | 1200–2200 m (3900–7200 ft) |
Distribution |
CA; LA; MA; MI; NJ; OH; OR; PA; WA; WI; BC; NB; NF; NS; PE; QC; Eurasia [Introduced in North America]
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CA; ID; MT; NV; OR; UT; WA; WY; AB; BC
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Discussion | 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.) |
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.) |
Source | FNA vol. 20, p. 563. | FNA vol. 20, p. 558. |
Parent taxa | Asteraceae > tribe Senecioneae > Senecio | Asteraceae > tribe Senecioneae > Senecio |
Sibling taxa | ||
Synonyms | S. foetidus, S. foetidus var. hydrophiloides, S. oreganus | |
Name authority | Linnaeus: Sp. Pl. 2: 868. (1753) | Rydberg: Mem. New York Bot. Gard. 1: 441. (1900) |
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