Hymenoxys cooperi

(A. Gray) Cockerell
Bull. Torrey Bot. Club 31: 494. 1904.
Common names: Cooper’s rubberweed or bitterweed
Endemic
Basionym: Actinella cooperi A. Gray Proc. Amer. Acad. Arts 7: 359. 1868
Synonyms: Hymenoxys cooperi var. canescens (D. C. Eaton) K. F. Parker
Treatment appears in FNA Volume 21. Treatment on page 442. Mentioned on page 435, 436, 437.

Biennials or perennials, (10–)20–80(–100) cm (monocarpic; sometimes with sparingly branched, woody caudices). Stems 1–3(–15), usually purple-red-tinted proximally, sometimes purple-red-tinted throughout, branched distally, ± hairy. Leaves: blades simple or lobed (lobes 3–9), ± hairy, gland-dotted (basal leaf bases ± long-villous-woolly); mid leaves lobed (lobes 3–5, terminal lobes 1–2.5 mm wide). Heads (1–)7–45(–80) per plant, in paniculiform to corymbiform arrays. Peduncles (2–)3.5–8(–13) cm, ± hairy. Involucres subhemispheric to hemispheric, 8–10 × 10–17 mm. Phyllaries in 2 series, unequal; outer 8–15, basally connate 1/3–1/2 their lengths (moderately to strongly keeled), lanceolate, 4.5–8.9 mm, apices acuminate to acute; inner 14–22, obovate to oblanceolate, 4.1–6.8 mm, apices acuminate to mucronate. Ray florets 9–14; corollas yellow, 10.2–17(–21.5) × 4–7.5(–9.2) mm. Disc florets 30–150+; corollas 2.7–4.8 mm. Cypselae narrowly obpyramidal, 1.7–3.7 mm; pappi of 5–6(–8) obovate, aristate scales 1.3–3.3 mm. 2n = 30.


Phenology: Flowering May–Jun(–Sep).
Habitat: Roadsides, open areas, edges of juniper-pine forests
Elevation: (1000–)1500–2500(–3500) m

Distribution

V21-1109-distribution-map.gif

Ariz., Calif., Idaho, Nev., Oreg., Utah.

Discussion

Some plants of Hymenoxys cooperi, mostly 10–40 cm with mostly 1–6 heads, have been called var. canescens.

Selected References

None.

Lower Taxa

None.

... more about "Hymenoxys cooperi"
Mark W. Bierner +
(A. Gray) Cockerell +
Actinella cooperi +
Cooper’s rubberweed or bitterweed +
Ariz. +, Calif. +, Idaho +, Nev. +, Oreg. +  and Utah. +
(1000–)1500–2500(–3500) m +
Roadsides, open areas, edges of juniper-pine forests +
Flowering May–Jun(–Sep). +
Bull. Torrey Bot. Club +
Hymenoxys cooperi var. canescens +
Hymenoxys cooperi +
Hymenoxys +
species +