Parthenium confertum |
Parthenium ligulatum |
|
---|---|---|
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 |
AZ; NM; TX; Mexico
|
CO; UT |
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 | ||
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) |
Web links |