Flora of North America species comparison

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Ivesia argyrocoma

Ivesia tweedyi

silver-hair ivesia, silverhair mousetail

Tweedy's ivesia, Tweedy's mousetail
Habit Plants green, ± rosetted to tufted; taproot stout, not fleshy.
Stems

ascending to erect, 0.4–2(–3.5) dm.
Basal leaves

loosely cylindric, (3–)4–12(–17) cm; sheathing base glabrous abaxially;

petiole 0.5–7 cm, hairs 1–1.5 mm;

leaflets 10–16 per side, 4–7(–10) mm, glabrous or sparsely hirsute, glandular-puberulent or -pubescent, lobes (2–)5–15, linear to narrowly oblanceolate, apex not setose.
Cauline leaves

(0–)1–2, not paired.
Inflorescences

(5–)10–25(–35)-flowered, (1–)1.5–3(–4.5) cm diam.;

glomerules 1–few.
Pedicels

1–3(–5) mm.
Flowers

9–12 mm diam.;

epicalyx bractlets linear, 1–2 mm;

hypanthium shallowly campanulate, 1–1.5 × 2–4(–5.5) mm;

sepals 2–3.5 mm, acute;

petals golden yellow, broadly elliptic to spatulate, 2.5–3.3 mm;

stamens 5, filaments 1–1.7 mm, anthers yellow, 0.5–0.8 mm;

carpels (2–)4–6(–9), styles 2–3 mm.
Achenes

olive green, 1.8–2 mm.

Ivesia argyrocoma

Ivesia tweedyi
Phenology Flowering summer.
Habitat Dry, gravelly to rocky flats, slopes, alpine ridges, often on serpentine, in subalpine conifer woodlands
Elevation 1600–2300 m (5200–7500 ft)
Distribution
from FNA
CA; nw Mexico
[WildflowerSearch map]
[BONAP county map]
from FNA
ID; MT; WA
[WildflowerSearch map]
[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.)

Of conservation concern.

Ivesia tweedyi is found from the Cascade Range in Washington to Boundary and Shoshone counties in Idaho, barely entering Montana in Mineral County.

(Discussion copyrighted by Flora of North America; reprinted with permission.)
Source FNA vol. 9, p. 242. FNA vol. 9, p. 235.
Parent taxa Rosaceae > subfam. Rosoideae > tribe Potentilleae > Ivesia > sect. Unguiculatae Rosaceae > subfam. Rosoideae > tribe Potentilleae > Ivesia > sect. Ivesia
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. rhypara, I. sabulosa, I. santolinoides, I. saxosa, I. sericoleuca, I. setosa, I. shockleyi, I. unguiculata, I. utahensis, I. webberi
Subordinate taxa
I. argyrocoma var. argyrocoma
Synonyms Horkelia argyrocoma, Potentilla argyrocoma Potentilla tweedyi
Name authority (Rydberg) Rydberg: in N. L. Britton et al., N. Amer. Fl. 22: 284. (1908) Rydberg: in N. L. Britton et al., N. Amer. Fl. 22: 288. (1908)
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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