Senecio triangularis |
Senecio riddellii |
|
---|---|---|
arrow-leaf groundsel, arrow-leaf ragwort, arrowleaf butterweed, groundsel |
Riddell's groundsel, Riddell's ragwort |
|
Habit | Perennials, (20–)50–120(–200) cm (caudices branched, ± woody). | Subshrubs, 30–100 cm (taproots forming woody crowns). |
Herbage | glabrous or sparsely floccose-tomentose when young. |
glabrous. |
Stems | single or loosely clustered. |
usually multiple (branching upward). |
Leaves | evenly distributed; petiolate; blades narrowly triangular, (3–)4–10+ × 2–6 cm, bases usually ± truncate, sometimes tapered, margins usually dentate, rarely subentire (distal leaves subsessile, smaller). |
± 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 | ± 8; corolla laminae 9–15 mm. |
± 8; corolla laminae (often falling early) 8–10 mm. |
Phyllaries | (± 8) ± 13 (± 21), 6–10 mm, tips usually green, rarely black. |
± 13, 7–10(–12+) mm, tips green. |
Calyculi | of 2–6 bractlets (rarely more than 2 mm). |
usually of 3–8+ lance-linear to filiform bractlets (lengths 1/10–1/3 phyllaries). |
Heads | 10–30(–60) in corymbiform to subracemiform arrays. |
5–20+ in close, corymbiform arrays (involucres campanulate, 7–10 mm diam.). |
Cypselae | glabrous. |
hirtellous. |
2n | = 40, 80. |
= 40. |
Senecio triangularis |
Senecio riddellii |
|
Phenology | Flowering summer. | Flowering mostly mid summer–fall, occasionally spring. |
Habitat | Damp places, open woodlands, especially rocky stream banks in coniferous forests | Sandy or rocky open sites, especially drying, open, flood plains |
Elevation | 100–3300 m (300–10800 ft) | 600–2500 m (2000–8200 ft) |
Distribution |
AK; AZ; CA; CO; ID; MT; NM; NV; OR; WA; WY; AB; BC; NT; YT; PH
|
AZ; CO; KS; NE; NM; OK; SD; TX; WY
|
Discussion | Plants of Senecio triangularis with narrow, subentire leaves that taper to the petioles are occasionally encountered in acid bogs in Oregon and Washington and less frequently elsewhere. They are regarded as edaphic variants; they have been recognized as var. angustifolius. (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. 566. | FNA vol. 20, p. 560. |
Parent taxa | Asteraceae > tribe Senecioneae > Senecio | Asteraceae > tribe Senecioneae > Senecio |
Sibling taxa | ||
Synonyms | S. gibbonsii, S. saliens, S. triangularis var. angustifolius | S. filifolius var. fremontii, S. riddellii var. parksii, S. spartioides var. fremontii, S. spartioides var. parksii, S. spartioides var. riddellii |
Name authority | Hooker: Fl. Bor.-Amer. 1: 332, plate 115. (1834) | Torrey & A. Gray: Fl. N. Amer. 2: 444. (1843) |
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