Senecio riddellii

Torrey & A. Gray

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

Endemic
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

Distribution

V20-1246-distribution-map.gif

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

Discussion

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

None.

Lower Taxa

None.
... more about "Senecio riddellii"
not tailed +, rounded +  and obtuse +
papillate +
scarious +
usually ovate +  and lance-linear +
indeterminate +  and determinate +
Theodore M. Barkley† +
Torrey & A. Gray +
decurrent +
4 cm40 mm <br />0.04 m <br /> (9 cm90 mm <br />0.09 m <br />) +
linear-filiform +
1mm;5mm +
winged;nerved;ribbed +
lance-linear;filiform +
barbellulate +  and smooth +
white +  and stramineous +
purplish +, reddish +, white +, ochroleucous +, yellow +  and white rarely reddish +
0.8 cm8 mm <br />0.008 m <br /> (1 cm10 mm <br />0.01 m <br />) +
angled +, 5-ribbed +, prismatic +  and cylindric +
fertile +  and bisexual +
fertile +  and bisexual +
Ariz. +, Colo. +, Kans. +, Nebr. +, N.Mex. +, Okla. +, S.Dak. +, Tex. +  and Wyo. +
600–2500 m +
hairy +  and glabrous +
pistillate +, staminate +  and neuter +
winged +  and beaked +
dispersed +
Sandy or rocky open sites, especially drying, open, flood plains +
discoid +  and radiate +
indeterminate +
heterogamous +  and homogamous +
each +  and sessile +
0.5 cm5 mm <br />0.005 m <br /> (1.5 cm15 mm <br />0.015 m <br />) +
turbinate;campanulate +
petiolate +  and sessile +
distributed +
cauline +  and basal +
4 cm40 mm <br />0.04 m <br /> (9 cm90 mm <br />0.09 m <br />) +
erect;recurved +
linear-filiform +
1mm +  and 5mm +
dentate to pinnatifid +  and entire +
2-carpellate +
persistent +
Flowering mostly mid summer–fall, occasionally spring. +
1 cm10 mm <br />0.01 m <br /> (1.2 cm12 mm <br />0.012 m <br />) +
mostly oblong +  and lanceolate or linear +
0.7 cm7 mm <br />0.007 m <br /> (1 cm10 mm <br />0.01 m <br />) +
Fl. N. Amer. +
bearing subulate enations +, hairy +  and bristly +
flat;convex +
exalbuminous +
appendaged +  and truncate +
papillate +
Senecio filifolius var. fremontii +, Senecio riddellii var. parksii +, Senecio spartioides var. fremontii +, Senecio spartioides var. parksii +  and Senecio spartioides var. riddellii +
Senecio riddellii +
species +
campanulate +
denticulate +  and serrate or toothed +
perennial +, biennial +  and annual +