Ivesia gordonii |
Ivesia tweedyi |
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alpine ivesia, alpine mousetail, Gordon's ivesia |
Tweedy's ivesia, Tweedy's mousetail |
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Habit | Plants green, ± tufted, sometimes rosetted; taproot stout, not fleshy. | Plants green, ± rosetted to tufted; taproot stout, not fleshy. | ||||||||||||
Stems | prostrate to erect, (0.2–)0.5–4 dm. |
ascending to erect, 0.4–2(–3.5) dm. |
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Basal leaves | tightly to loosely cylindric, (1–)3–20(–25) cm; sheathing base ± glandular abaxially, otherwise glabrous; petiole 0.5–8 cm, hairs 0.2–0.5 mm; leaflets (6–)10–25 per side, (1–)2–13(–18) mm, glabrous or ± hirsute or villous, glandular-puberulent or -pubescent, lobes (2–)4–8(–15), linear or narrowly oblanceolate to obovate, apex rarely setose. |
loosely cylindric, (3–)4–12(–17) cm; sheathing base glabrous abaxially; petiole 0.5–7 cm, hairs 1–1.5 mm; leaflets 10–16 per side, 4–7(–10) mm, glabrous or sparsely hirsute, glandular-puberulent or -pubescent, lobes (2–)5–15, linear to narrowly oblanceolate, apex not setose. |
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Cauline leaves | 1(–2), not paired. |
(0–)1–2, not paired. |
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Inflorescences | 5–50(–70)-flowered, 1–8(–11) cm diam.; glomerules 1–several. |
(5–)10–25(–35)-flowered, (1–)1.5–3(–4.5) cm diam.; glomerules 1–few. |
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Pedicels | 1–3(–5) mm. |
1–3(–5) mm. |
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Flowers | 5–12 mm diam.; epicalyx bractlets linear to narrowly elliptic, (0.5–)1–3.5(–4) mm; hypanthium turbinate to campanulate, (1.5–)2–4(–4.5) × 2–4(–5) mm; sepals (2–)2.5–5(–6) mm, obtuse to ± acute; petals yellow, narrowly oblanceolate to narrowly spatulate, (1–)1.5–3 mm; stamens 5, filaments 1.3–2.5 mm, anthers yellow, sometimes red-margined, 0.5–1 mm; carpels (1–)2–4(–6), styles 2.5–4.5(–6) mm. |
9–12 mm diam.; epicalyx bractlets linear, 1–2 mm; hypanthium shallowly campanulate, 1–1.5 × 2–4(–5.5) mm; sepals 2–3.5 mm, acute; petals golden yellow, broadly elliptic to spatulate, 2.5–3.3 mm; stamens 5, filaments 1–1.7 mm, anthers yellow, 0.5–0.8 mm; carpels (2–)4–6(–9), styles 2–3 mm. |
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Achenes | grayish brown to mottled brown, ± 2 mm. |
olive green, 1.8–2 mm. |
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Ivesia gordonii |
Ivesia tweedyi |
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Phenology | Flowering summer. | |||||||||||||
Habitat | Dry, gravelly to rocky flats, slopes, alpine ridges, often on serpentine, in subalpine conifer woodlands | |||||||||||||
Elevation | 1600–2300 m (5200–7500 ft) | |||||||||||||
Distribution |
CA; CO; ID; MT; NV; OR; UT; WA; WY
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ID; MT; WA
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Discussion | Varieties 4 (4 in the flora). Ivesia gordonii is the most widespread species of the genus, occurring from Washington to Montana, south to central California and Colorado. The species can be distinguished from other members of sect. Ivesia by the relatively deep hypanthium, which is about as deep as wide. Four varieties are provisionally recognized here (B. Ertter and J. L. Reveal 2007), with the likelihood that future work may indicate additional and/or alternate circumscriptions. Populations that are difficult to assign to a variety can be found where the recognizable taxonomic units come together, for example, in northeastern Utah and western Wyoming, involving var. gordonii and var. wasatchensis, and in California and central Idaho where var. alpicola and var. ursinorum tend to merge. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Of conservation concern. Ivesia tweedyi is found from the Cascade Range in Washington to Boundary and Shoshone counties in Idaho, barely entering Montana in Mineral County. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
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Key |
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Source | FNA vol. 9, p. 233. | FNA vol. 9, p. 235. | ||||||||||||
Parent taxa | Rosaceae > subfam. Rosoideae > tribe Potentilleae > Ivesia > sect. Ivesia | Rosaceae > subfam. Rosoideae > tribe Potentilleae > Ivesia > sect. Ivesia | ||||||||||||
Sibling taxa | ||||||||||||||
Subordinate taxa | ||||||||||||||
Synonyms | Horkelia gordonii, Potentilla gordonii | Potentilla tweedyi | ||||||||||||
Name authority | (Hooker) Torrey & A. Gray: in War Department [U.S.], Pacif. Railr. Rep. 6(3): 72. (1858) | Rydberg: in N. L. Britton et al., N. Amer. Fl. 22: 288. (1908) | ||||||||||||
Web links |