Senecio riddellii

Torrey & A. Gray

Fl. N. Amer. 2: 444. 1843.

Synonyms: Senecio filifolius var. fremontii Torrey & A. Gray Senecio riddellii var. parksii Cory Senecio spartioides var. fremontii (Torrey & A. Gray) Greenman Senecio spartioides var. parksii (Cory) Shinners Senecio spartioides var. riddellii (Torrey & A. Gray) Greenman
Treatment appears in FNA Volume 20. Treatment on page 560. Mentioned on page 548.

Subshrubs, 30–100 cm (taproots forming woody crowns). Herbage glabrous. Stems usually multiple (branching upward). Leaves ± 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. Heads 5–20+ in close, corymbiform arrays (involucres campanulate, 7–10 mm diam.). Calyculi usually of 3–8+ lance-linear to filiform bractlets (lengths 1/10–1/3 phyllaries). Phyllaries ± 13, 7–10(–12+) mm, tips green. Ray florets ± 8; corolla laminae (often falling early) 8–10 mm. Cypselae hirtellous. 2n = 40.

Phenology: Flowering mostly mid summer–fall, occasionally spring.
Habitat: Sandy or rocky open sites, especially drying, open, flood plains
Elevation: 600–2500 m



Ariz., Colo., Kans., Nebr., N.Mex., Okla., S.Dak., Tex., Wyo.


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.

Selected References


Lower Taxa

... more about "Senecio riddellii"
Theodore M. Barkley† +
Torrey & A. Gray +
Ariz. +, Colo. +, Kans. +, Nebr. +, N.Mex. +, Okla. +, S.Dak. +, Tex. +  and Wyo. +
600–2500 m +
Sandy or rocky open sites, especially drying, open, flood plains +
Flowering mostly mid summer–fall, occasionally spring. +
Fl. N. Amer. +
Senecio filifolius var. fremontii +, Senecio riddellii var. parksii +, Senecio spartioides var. fremontii +, Senecio spartioides var. parksii +  and Senecio spartioides var. riddellii +
Senecio riddellii +
species +