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gray feverfew, Gray's feverfew

Colorado feverfew

Habit Biennials (sometimes flowering first year or persisting), 10–30(–60+) cm. Perennials, 1–2 cm (underground caudices 2–5+ cm, branched; plants cespitose or forming mats).
Leaf

blades ovate or rounded-deltate to elliptic, 30–80(–120+) × 10–20(–40+) mm, usually ± pinnately or sub-bipinnately lobed, ultimate margins entire, faces strigillose, usually also with erect hairs 1–2 mm and gland-dotted.

blades oblanceolate to spatulate, 5–18+ × 1–2(–4+) mm, margins entire, faces strigilloso-sericeous (gray) and obscurely gland-dotted.

Peduncles

2–8(–12+) mm.

0–4 mm.

Pistillate florets

5;

corolla laminae 0 or ± coroniform, 0.1–0.5 mm.

5;

corolla laminae oval to elliptic, 1–2 mm, retuse.

Disc florets

20–30+.

15–25+.

Phyllaries

outer 5 lance-ovate to elliptic, 2.5–3+ mm, inner 5 ± orbiculate, 3–3.5 mm.

outer 5 ± ovate, 2.5–3 mm, inner 5 ± orbiculate, 3–4+ mm.

Heads

disciform or obscurely radiate, borne in open, ± paniculiform arrays.

radiate, borne singly.

Cypselae

± obovoid, 2–3 mm; pappus-like enations 2, ± erect, deltate to ovate, 0.5–1 mm (sometimes a third, subulate spur near apex adaxially).

oblanceoloid to pyriform, 3.5–4 mm; pappus-like enations 2, erect to spreading, ± subulate, 0.5–1 mm (a third, ± subulate element sometimes at apex of adaxial face).

2n

= 36, 68, 72.

= 36, 72.

Parthenium confertum

Parthenium ligulatum

Phenology Flowering Mar–Oct. Flowering May–Jun.
Habitat Sandy plains, openings in mesquite grasslands Pale shale or sandstone outcrops with pinyon-juniper
Elevation 20–2000 m (100–6600 ft) 1800–2000 m (5900–6600 ft)
Distribution
from FNA
AZ; NM; TX; Mexico
[WildflowerSearch map]
[BONAP county map]
from FNA
CO; UT
[BONAP county map]
Source FNA vol. 21, p. 22. FNA vol. 21, p. 21.
Parent taxa Asteraceae > tribe Heliantheae > subtribe Ambrosiinae > Parthenium Asteraceae > tribe Heliantheae > subtribe Ambrosiinae > Parthenium
Sibling taxa
P. alpinum, P. argentatum, P. hysterophorus, P. incanum, P. integrifolium, P. ligulatum
P. alpinum, P. argentatum, P. confertum, P. hysterophorus, P. incanum, P. integrifolium
Synonyms P. confertum var. divaricatum, P. confertum var. lyratum, P. confertum var. microcephalum P. alpinum var. ligulatum
Name authority A. Gray: Proc. Amer. Acad. Arts 17: 216. (1882) (M. E. Jones) Barneby: Leafl. W. Bot. 5: 20. (1947)
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