Ivesia gordonii |
Ivesia pygmaea |
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alpine ivesia, alpine mousetail, Gordon's ivesia |
dwarf ivesia, dwarf mousetail |
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Habit | Plants green, ± tufted, sometimes rosetted; taproot stout, not fleshy. | Plants green, tufted to ± tightly matted; taproot stout, not fleshy. | ||||||||||||
Stems | prostrate to erect, (0.2–)0.5–4 dm. |
decumbent to erect, 0.3–1(–1.5) 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. |
tightly cylindric, (0.5–)1–8(–12) cm; sheathing base usually ± strigose abaxially; petiole 0.5–4 cm, hairs 0.2–1 mm; leaflets 10–15(–20) per side, 0.5–4(–5) mm, sparsely to moderately short-villous, densely glandular, lobes 3–6(–8), oblanceolate to narrowly oblong or oval, apex setose. |
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Cauline leaves | 1(–2), not paired. |
(0–)1, not paired. |
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Inflorescences | 5–50(–70)-flowered, 1–8(–11) cm diam.; glomerules 1–several. |
(1–)5–10-flowered, 0.8–3 cm diam.; glomerules usually 1. |
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Pedicels | 1–3(–5) mm. |
1.5–8(–10) 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. |
9–11 mm diam.; epicalyx bractlets elliptic to oblong, 1.2–2 mm; hypanthium shallowly cupulate, 1–2 × 2.5–5(–7) mm; sepals 2–3.5 mm, bluntly acute; petals golden yellow, broadly oblanceolate to spatulate or broadly obovate, (2–)2.5–3.5(–4) mm; stamens 10, filaments 0.6–1.8 mm, anthers yellow, 0.6–0.8 mm; carpels 10–30, styles 0.9–1.3 mm. |
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Achenes | grayish brown to mottled brown, ± 2 mm. |
greenish tan to light brown, 1.2–1.5 mm. |
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Ivesia gordonii |
Ivesia pygmaea |
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Phenology | Flowering summer. | |||||||||||||
Habitat | Dry rocky slopes, sometimes in horizontal rock crevices, in high-elevation sagebrush communities, subalpine to alpine conifer woodlands, alpine tundra | |||||||||||||
Elevation | 2700–4000 m (8900–13100 ft) | |||||||||||||
Distribution |
CA; CO; ID; MT; NV; OR; UT; WA; WY
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CA
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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.) |
Ivesia pygmaea is known only from the southern Sierra Nevada in California, where it overlaps the range of I. lycopodioides var. megalopetala. Stamen number is the only unequivocal way to distinguish between the two, though I. pygmaea is also more generally setose with somewhat shallower hypanthia. It is also more likely to have much-branched caudices and can form mats in rocky sites. Larger plants with relatively open cymes have sometime been segregated as I. chaetophora; this probably represents ecological and phenotypic plasticity. Early reports of Ivesia pygmaea from Nevada are based on P. A. Rydberg’s (1898) mistaken understanding of the type locality, which is actually in Tulare County, California. A reported occurrence from the northern Sierra Nevada in Nevada (J. T. Kartesz 1987) is presumably based on the same source as the unconfirmed report of I. lycopodioides from the same locality (D. D. Keck 1938). The correct name for this species if treated as Potentilla is P. nubigena Greene; P. decipiens Greene is a later homonym and illegitimate. (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. 231. | ||||||||||||
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 | I. chaetophora, I. gordonii var. pygmaea, Potentilla gordonii var. chaetophora, P. nubigena | ||||||||||||
Name authority | (Hooker) Torrey & A. Gray: in War Department [U.S.], Pacif. Railr. Rep. 6(3): 72. (1858) | A. Gray: Proc. Amer. Acad. Arts 6: 531. (1865) | ||||||||||||
Web links |