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Ivesia gordonii

alpine ivesia, alpine mousetail, Gordon's ivesia

Bailey's ivesia, Owyhee ivesia

Habit Plants green, ± tufted, sometimes rosetted; taproot stout, not fleshy. Plants green, ± tufted, often forming hanging clumps, sometimes rosetted.
Stems

prostrate to erect, (0.2–)0.5–4 dm.

pendent or prostrate to ascending, 0.5–2(–2.5) 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.

planar, 3–12(–18) cm; sheathing base not or sparsely strigose abaxially;

petiole 1–8 cm;

lateral leaflets 2–6(–10) per side, separate to slightly overlapping distally, ovate or obovate to flabellate, 4–15(–25) mm, incised 1/4–3/4 to base into 3–11(–15) ovate to oblanceolate teeth or lobes, apex not setose, surfaces ± sparsely short-pilose or hirsute, ± glandular;

terminal leaflets ± distinct.

Cauline leaves

1(–2), not paired.

1–2;

blade reduced.

Inflorescences

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

glomerules 1–several.

(1–)5–40-flowered, open, (1–)1.5–8(–10) cm diam.

Pedicels

1–3(–5) mm.

2–15(–30) mm.

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.

4–10 mm diam.;

epicalyx bractlets 5, narrowly lanceolate to ovate, 0.8–2.5 mm;

hypanthium patelliform, 0.5–2 × 2–4 mm;

sepals (1.2–)1.5–4 mm, acute;

petals white or pale yellow, oblanceolate to narrowly spatulate, 1.5–2.5 mm;

stamens 5, filaments 0.5–1.1 mm, anthers yellow, sometimes with reddish margins, oblong, 0.4–0.7 mm;

carpels (1–)3–8, styles 0.9–1.8 mm.

Achenes

grayish brown to mottled brown, ± 2 mm.

greenish white to light tan, 1.5–2 mm, smooth or rugose, ± carunculate.

Ivesia gordonii

Ivesia baileyi

Distribution
from FNA
CA; CO; ID; MT; NV; OR; UT; WA; WY
[WildflowerSearch map]
[BONAP county map]
from FNA
CA; ID; NV; OR
[WildflowerSearch map]
[BONAP county map]
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.)

Varieties 2 (2 in the flora).

The two varieties accepted here were not recognized by D. D. Keck (1938), who instead treated Ivesia setosa as a variety of I. baileyi. Field investigations confirm that the three entities are reasonably distinct morphologically, with intergradation where their otherwise distinct ranges overlap in central Nevada.

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

Key
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. Petals pale yellow; hypanthium interior yellow to golden; epicalyx bractlets ± 3/4 to as long as sepals; achenes smooth.
var. baileyi
1. Petals white; hypanthium interior pale green or cream to maroon; epicalyx bractlets usually less than 1/2 as long as sepals; achenes rugose.
var. beneolens
Source FNA vol. 9, p. 233. FNA vol. 9, p. 226.
Parent taxa Rosaceae > subfam. Rosoideae > tribe Potentilleae > Ivesia > sect. Ivesia Rosaceae > subfam. Rosoideae > tribe Potentilleae > Ivesia > sect. Setosae
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
I. aperta, I. argyrocoma, I. arizonica, I. callida, I. campestris, I. cryptocaulis, I. gordonii, 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. baileyi var. baileyi, I. baileyi var. beneolens
Synonyms Horkelia gordonii, Potentilla gordonii Potentilla baileyi
Name authority (Hooker) Torrey & A. Gray: in War Department [U.S.], Pacif. Railr. Rep. 6(3): 72. (1858) S. Watson: Botany (Fortieth Parallel), 90. (1871)
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