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Utah ivesia, Utah mousetail

purpusia, rock whitefeather

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

prostrate to ascending, 0.5–1.5(–2) dm.

pendent or prostrate to ascending, (0.2–)0.5–1.6(–3) dm.

Basal leaves

± tightly cylindric, 2–7(–9) cm; sheathing base glabrous abaxially;

petiole 0.5–2 cm, hairs 0.5–1 mm;

leaflets 15–20 per side, 2–4 mm, glabrate or sparsely short-hirsute, sparsely to densely glandular, lobes (2–)3–8, narrowly oblanceolate to obovate, apex not setose.

planar, 2–15(–20) cm; sheathing base usually not strigose abaxially;

petiole 3–10 cm;

lateral leaflets (2–)3–4(–5) per side, separate, broadly ovate or obovate to orbiculate, (2–)5–15(–18) mm, incised 1/4–3/4 to base into (3–)7–11 ± ovate teeth, apex not setose, surfaces ± sparsely short-pilose, ± glandular;

terminal leaflets ± distinct.

Cauline leaves

(0–)1, not paired.

1–3;

blade well developed.

Inflorescences

(5–)10–30-flowered, 1–2.5(–5) cm diam.;

glomerules 1–few.

(1–)5–30(–150)-flowered, open, 0.5–14 cm diam.

Pedicels

1–7 mm.

5–30 mm.

Flowers

7–9 mm diam.;

epicalyx bractlets narrowly oblong to oval, 0.8–2 mm;

hypanthium shallowly cupulate, (1–)1.5–2 × 2.5–3.5 mm;

sepals (1.8–)2–3 mm, acute;

petals white, sometimes pink-tinged, oblanceolate to spatulate, 1.8–3 mm;

stamens 5, filaments 1.3–1.8 mm, anthers orangish to reddish brown, 0.4–0.6 mm;

carpels (1–)2–4, styles 1.5–2 mm.

6–12 mm diam.;

epicalyx bractlets 0(–3), lanceolate, 0.9–1.8 mm;

hypanthium turbinate or campanulate, 1.5–3(–5) × 1–3(–4) mm;

sepals 2–4(–5) mm, acute;

petals yellow or white, oblanceolate to elliptic or obovate, (1.6–)2–4 mm;

stamens 5, filaments 0.8–1.3 mm, anthers ± yellow, oblong to narrowly ovate, 0.6–1.5 mm;

carpels (2–)6–10(–13), atop a stipelike torus, styles 0.9–1.8 mm.

Achenes

yellowish green to light tan or gray-brown, 1.7–1.9 mm.

greenish white to light tan, 1.2–2 mm, faintly rugose, ± carunculate.

Ivesia utahensis

Ivesia arizonica

Phenology Flowering summer.
Habitat Talus slopes, bare ridges, in high-elevation sagebrush communities, subalpine to alpine conifer woodlands
Elevation 3200–3700 m (10500–12100 ft)
Distribution
from FNA
UT
[BONAP county map]
from FNA
AZ; CA; NV; UT
[BONAP county map]
Discussion

Of conservation concern.

Ivesia utahensis is known from the Wasatch and adjacent Uinta Mountains in northern Utah. The species stands as the white-petaled counterpart to the yellow-petaled Sierran I. lycopodioides, possibly indicating a common ancestral stock that was once more continuous across the Great Basin.

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

Varieties 2 (2 in the flora).

Because the epithet saxosa was retained for Potentilla saxosa upon transfer to Ivesia, a different epithet (arizonica) was needed when Purpusia was likewise transferred in the same publication (B. Ertter 1989). The correct name for this species in Potentilla is P. osterhoutii (A. Nelson) J. T. Howell, due to the existence of P. arizonica.

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

Key
1. Petals yellow; hypanthia campanulate.
var. arizonica
1. Petals white; hypanthia turbinate.
var. saxosa
Source FNA vol. 9, p. 233. FNA vol. 9, p. 224.
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. 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. webberi
I. aperta, I. argyrocoma, I. baileyi, 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. arizonica var. arizonica, I. arizonica var. saxosa
Synonyms Potentilla utahensis Purpusia arizonica
Name authority S. Watson: Proc. Amer. Acad. Arts 17: 371. (1882) (Eastwood ex J. T. Howell) Ertter: Syst. Bot. 14: 233. (1989)
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