Flora of North America species comparison

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Ivesia argyrocoma

Ivesia rhypara

silver-hair ivesia, silverhair mousetail

grimy ivesia, grimy mousetail
Habit Plants grayish, ± matted.
Stems

± prostrate, (0.1–)0.2–1.5(–2) dm.
Basal leaves

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

(0–)1;

blade vestigial.
Inflorescences

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

1.5–4(–8) mm.
Flowers

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

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

Ivesia argyrocoma

Ivesia rhypara
Distribution
from FNA
CA; nw Mexico
[WildflowerSearch map]
[BONAP county map]
from FNA
NV; OR
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[BONAP county map]
Discussion

Varieties 2 (1 in the flora).

Plants from the central Sierra San Pedro Mártir in northern Baja California belong to var. moranii Ertter & Reveal, which may be distinguished by its compact stature (to 0.5 dm), densely villous basal stipules 2–4 mm, decumbent stems 2–7 cm that are stipitate-glandular under the villous indumentum, and solitary, loosely congested cyme. The petals are oblanceolate to narrowly obovate and 2.5–3.5 mm. The grayish, faintly mottled achenes are 1.3–2 mm.

(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. 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. 242. FNA vol. 9, p. 228.
Parent taxa Rosaceae > subfam. Rosoideae > tribe Potentilleae > Ivesia > sect. Unguiculatae Rosaceae > subfam. Rosoideae > tribe Potentilleae > Ivesia > sect. Setosae
Sibling taxa
I. aperta, 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. 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. argyrocoma var. argyrocoma
I. rhypara var. rhypara, I. rhypara var. shellyi
Synonyms Horkelia argyrocoma, Potentilla argyrocoma
Name authority (Rydberg) Rydberg: in N. L. Britton et al., N. Amer. Fl. 22: 284. (1908) Ertter & Reveal: Madroño 24: 224, fig. 1. (1977)
Web links 
Unless otherwise noted, all data comes from the online version of the Flora of North America, who have made most of their content available via a Creative Commons license (CC BY 4.0).



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