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purpusia, rock whitefeather

grimy ivesia, grimy mousetail

Habit Plants green, ± tufted, often forming hanging clumps, sometimes rosetted. Plants grayish, ± matted.
Stems

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

± prostrate, (0.1–)0.2–1.5(–2) dm.

Basal leaves

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.

tightly cylindric, 2–10 cm; sheathing base densely hairy abaxially;

petiole 0.5–4(–10) cm;

lateral leaflets 4–10(–15) per side, overlapping at least distally, ± flabellate, 0.5–3(–4) mm, incised to base or nearly so into (0–)2–4(–9) elliptic to obovate or orbiculate lobes, apex usually not setose, surfaces densely hirsute, cryptically glandular;

terminal leaflets indistinct.

Cauline leaves

1–3;

blade well developed.

(0–)1;

blade vestigial.

Inflorescences

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

5–60(–100)-flowered, congested, 0.5–5(–7) cm diam.

Pedicels

5–30 mm.

1.5–4(–8) mm.

Flowers

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.

4–8 mm diam.;

epicalyx bractlets 5, linear to elliptic or narrowly ovate, 0.8–1.6(–2.1) mm;

hypanthium patelliform to shallowly cupulate, 1–1.5 × (1.5–)2–3(–3.5) mm;

sepals 1.4–2.5(–2.8) mm, acute;

petals white to pale yellowish, linear to narrowly oblanceolate, 1–1.5 mm;

stamens 5, filaments 0.6–1.8 mm, anthers maroon or yellow with maroon margins, oblong, 0.3–0.6 mm;

carpels 1–2(–4), styles 1–1.5 mm.

Achenes

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

brown, 1.2–1.6(–2) mm, smooth, prominently carunculate.

Ivesia arizonica

Ivesia rhypara

Distribution
from FNA
AZ; CA; NV; UT
[BONAP county map]
from FNA
NV; OR
[WildflowerSearch map]
[BONAP county map]
Discussion

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.)

Varieties 2 (2 in the flora).

Ivesia rhypara forms densely hairy mats or mounds on isolated edaphic sites in the northern Great Basin. Only one of the widely disjunct population clusters is recognized as a distinct variety; the others have general differences in gestalt, but no significant distinctions have been determined (B. Ertter 1989). Isozyme analysis likewise does not show significant differences (T. Kaye et al., unpubl., BLM and Oregon Dept. of Agriculture, 1991). Reproductive studies by D. Wiens (pers. comm.) show low seed set (ca. 5% in var. rhypara, somewhat higher in var. shellyi), possibly indicating a deleterious genetic load.

(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
1. Plants (4–)8–30 cm diam.; inflorescences (1–)2–5(–7) cm diam.; scarcely or cryptically petrophytic in bedrock overlain by rubble and soil.
var. rhypara
1. Plants 2–10(–15) cm diam.; inflorescences 0.5–2(–5) cm diam.; overtly petrophytic in boulders and outcrops.
var. shellyi
Source FNA vol. 9, p. 224. FNA vol. 9, p. 228.
Parent taxa Rosaceae > subfam. Rosoideae > tribe Potentilleae > Ivesia > sect. Setosae Rosaceae > subfam. Rosoideae > tribe Potentilleae > Ivesia > sect. Setosae
Sibling taxa
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
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. 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
I. rhypara var. rhypara, I. rhypara var. shellyi
Synonyms Purpusia arizonica
Name authority (Eastwood ex J. T. Howell) Ertter: Syst. Bot. 14: 233. (1989) Ertter & Reveal: Madroño 24: 224, fig. 1. (1977)
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