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Ivesia gordonii

alpine ivesia, alpine mousetail, Gordon's ivesia

Habit Plants green, ± tufted, sometimes rosetted; taproot stout, not fleshy. Plants usually rosetted or tufted, rarely ± matted (I. pygmaea), not forming hanging clumps (not in vertical rock crevices except I. longibracteata), ± aromatic; taproot stout to fusiform and fleshy.

prostrate to erect, (0.2–)0.5–4 dm.

(0.2–)0.3–2(–4) dm.

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.

usually loosely to very tightly cylindric (mousetail-like in I. muirii), rarely weakly planar (I. longibracteata);

stipules present;

leaflets overlapping, individually distinguishable or not, lobed to base, sparsely to densely hairy, sometimes glabrous or glabrate;

terminal leaflets indistinct.

Cauline leaves

1(–2), not paired.

(0–)1–3, sometimes paired;

blade usually ± reduced to vestigial, rarely well developed.


5–50(–70)-flowered, 1–8(–11) cm diam.;

glomerules 1–several.

usually ± congested, sometimes becoming open in fruit, flowers mostly arranged in 1–few(–several in I. gordonii var. wasatchensis) loose to capitate glomerules.


1–3(–5) mm.

remaining straight.


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.

hypanthium shallowly cupulate or campanulate, sometimes turbinate (I. gordonii);

petals not medially reflexed, golden to pale yellow, sometimes white (I. utahensis) and then sometimes pink-tinged, not or scarcely clawed, apex acute to truncate, rounded, or emarginate;

stamens 5 (10 in I. pygmaea), anthers longer than wide, laterally dehiscent;

carpels (1–)2–15(–30 in I. pygmaea).


grayish brown to mottled brown, ± 2 mm.

vertical, smooth or nearly so, not carunculate.

Ivesia gordonii

Ivesia sect. Ivesia

from FNA
[WildflowerSearch map]
[BONAP county map]
w United States

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.)

Species 8 (8 in the flora).

Species in sect. Ivesia tend to form compact rosettes or tufts in open montane to alpine areas, often where rocky but generally not growing in rock crevices (except Ivesia longibracteata). General characteristics of the section are an overall evident glandularity, loosely to tightly cylindric leaves (mousetail-like in I. muirii), relatively short ascending to erect stems, straight pedicels, and flowers that are typically congested into 1–few capitate clusters that sometimes become more open in fruit. The taproots of some species, especially I. lycopodioides, are markedly enlarged, an adaptation to alpine growing conditions. The inclusion of two anomalous species in the section, I. longibracteata and I. webberi, is tentative; it is also possible that I. cryptocaulis belongs here rather than in sect. Setosae.

Section Ivesia has its center of species diversity in the high Sierra Nevada of California, where Ivesia pygmaea, with its ten stamens and more open habit, is possibly transitional between sects. Ivesia and Setosae. Ivesia gordonii (the most widespread species), I. tweedyi, and I. utahensis form an arc around the northern Great Basin, as outliers from the core Sierran distribution of the section.

Some early floras treated Ivesia pygmaea and I. lycopodioides as varieties of I. gordonii (for example, W. H. Brewer et al. 1876–1880, vol. 1) or Potentilla gordonii (Hooker) Greene (W. L. Jepson [1923–1925], 1909–1943, vol. 2). Recent treatments follow D. D. Keck (1938) in recognizing all three as distinct species; some annotations and references are nevertheless carried over from the earlier expanded circumscription of I. gordonii.

Since Ivesia cryptocaulis is sometimes identified as a member of sect. Ivesia, it is included herein and keys out in the seventh couplet.

(Discussion copyrighted by Flora of North America; reprinted with permission.)

1. Leaflets 7–13(–18) mm, glabrous or sparsely hirsute or villous marginally; stems (1–)1.5–4 dm; inflorescences usually branched, 2–8(–11) cm diam., glomerules (1–)2–6(–10), ± capitate.
var. wasatchensis
1. Leaflets (1–)2–7(–9) mm, hairy or ± glabrous except marginally ciliate; stems (0.2–)0.5–2.5 dm; inflorescences simple or branched, 1–3(–5) cm diam., glomerules 1(–3), ± capitate to loosely congested
→ 2
2. Stems usually prostrate to ascending, rarely nearly erect, usually dark reddish, minutely glandular or glandular-puberulent to -pubescent; leaves to 0.8 cm diam.; anthers usually red-margined.
var. ursinorum
2. Stems usually ascending to erect, sometimes decumbent, usually greenish, rarely reddish, hirsute to villous, glandular-puberulent to -pubescent; leaves to 1.5 cm diam.; anthers rarely red-margined
→ 3
3. Stems usually hirsute to villous, sometimes densely so, glandular-pubescent or eglandular; basal leaves (3–)5–10(–15) cm; flowers 7–12 mm diam.; e Idaho and w Montana to Utah, Wyoming, and w Colorado.
var. gordonii
3. Stems not or sparsely hirsute to villous, glandular-puberulent or -pubescent; basal leaves 2–8(–10) cm; flowers 5–9 mm diam.; s Washington to California and e to w Montana.
var. alpicola
1. Epicalyx bractlets longer than sepals, 2.5–5 mm; leaves weakly planar to loosely ± cylindric; leaflets 5–6 per side; Castle Crags, n California.
I. longibracteata
1. Epicalyx bractlets shorter than sepals, 0.5–3(–4 in I. gordonii) mm; leaves loosely to tightly cylindric; leaflets mostly 10–40 per side (4–10 in I. webberi); w United States
→ 2
2. Plants silvery; leaves very tightly cylindric (mousetail-like, with leaflets scarcely distinguishable); leaflets 0.4–1 mm.
I. muirii
2. Plants ± green; leaves loosely to tightly cylindric; leaflets distinguishable, (0.5–)2–13(–18) mm
→ 3
3. Cauline leaves 2, paired; basal leaves: leaflets 4–8(–10) per side; petiole hairs 2–4 mm.
I. webberi
3. Cauline leaves 0–2(–3), not paired; basal leaves: leaflets (6–)10–35 per side; petiole hairs 0.2–1.5 mm
→ 4
4. Hypanthia turbinate to campanulate, (1.5–)2–4(–4.5) mm (± as deep as wide); petals narrowly oblanceolate to narrowly spatulate.
I. gordonii
4. Hypanthia shallowly cupulate or shallowly campanulate, 1–2 mm (wider than deep); petals oblanceolate or broadly elliptic to spatulate or broadly obovate
→ 5
5. Carpels (1–)2–6(–9); Idaho, Utah, Washington
→ 6
5. Carpels (5–)8–30; e California, Nevada
→ 7
6. Petals white, sometimes pink-tinged; stems prostrate to ascending; leaflets 2–4 mm; Utah.
I. utahensis
6. Petals golden yellow; stems ascending to erect; leaflets 4–7(–10) mm; n Idaho, Washington.
I. tweedyi
7. Plants diffusely matted; Spring Mountains, s Nevada.
I. cryptocaulis
7. Plants rosetted to tufted or ± tightly matted; Sierra Nevada, White Mountains, and Sweetwater Mountains of e California and adjacent w Nevada
→ 8
8. Stamens 10; sheathing bases usually ± strigose abaxially; taproots stout, not fleshy.
I. pygmaea
8. Stamens 5; sheathing bases glabrous abaxially; taproots fusiform, fleshy.
I. lycopodioides
Source FNA vol. 9, p. 233. FNA vol. 9, p. 230.
Parent taxa Rosaceae > subfam. Rosoideae > tribe Potentilleae > Ivesia > sect. Ivesia Rosaceae > subfam. Rosoideae > tribe Potentilleae > Ivesia
Sibling taxa
I. aperta, I. argyrocoma, I. arizonica, I. baileyi, I. callida, I. campestris, I. cryptocaulis, I. jaegeri, I. kingii, I. longibracteata, I. lycopodioides, I. muirii, I. multifoliolata, I. paniculata, I. patellifera, I. pickeringii, I. pityocharis, I. pygmaea, I. rhypara, I. sabulosa, I. santolinoides, I. saxosa, I. sericoleuca, I. setosa, I. shockleyi, I. tweedyi, I. unguiculata, I. utahensis, I. webberi
Subordinate taxa
I. gordonii var. alpicola, I. gordonii var. gordonii, I. gordonii var. ursinorum, I. gordonii var. wasatchensis
I. cryptocaulis, I. gordonii, I. longibracteata, I. lycopodioides, I. muirii, I. pygmaea, I. tweedyi, I. utahensis, I. webberi
Synonyms Horkelia gordonii, Potentilla gordonii Horkelia unranked Lycopodioides, I. unranked Lycopodioides, I. section Lycopodioides
Name authority (Hooker) Torrey & A. Gray: in War Department [U.S.], Pacif. Railr. Rep. 6(3): 72. (1858) unknown
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