Flora of North America species comparison

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Ivesia tweedyi

Ivesia paniculata

Tweedy's ivesia, Tweedy's mousetail

Ash Creek ivesia, Ash Creek mousetail
Habit Plants green, ± rosetted to tufted; taproot stout, not fleshy. Plants grayish, ± matted.
Stems

ascending to erect, 0.4–2(–3.5) dm.

± prostrate, 0.4–1.5(–2) 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.

tightly cylindric, (1.5–)2–5(–7) cm; sheathing base densely hairy abaxially;

petiole 0.5–4 cm;

lateral leaflets (5–)8–15 per side, overlapping at least distally, ± flabellate, 0.5–2 mm, incised to base or nearly so into (0–)3–8(–15) elliptic to narrowly obovate lobes, apex not or obscurely setose, surfaces densely hirsute, cryptically glandular;

terminal leaflets indistinct.
Cauline leaves

(0–)1–2, not paired.

(0–)1;

blade reduced.
Inflorescences

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

glomerules 1–few.

20–200-flowered, congested, (1–)1.5–6(–10) cm diam.
Pedicels

1–3(–5) mm.

1.5–6 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.

4–6 mm diam.;

epicalyx bractlets 5, lanceolate to elliptic, 0.6–1.5(–2) mm;

hypanthium shallowly cupulate, 1 × 2–3 mm;

sepals (1–)1.5–2.5(–3) mm, acute;

petals white to pale yellowish, linear, 1 mm;

stamens 5, filaments 0.3–1 mm, anthers yellow with maroon margins, ovate, 0.3–0.5 mm;

carpels 1–2(–3), styles 0.7–1.8 mm.
Achenes

olive green, 1.8–2 mm.

brown, 0.8–1.5 mm, smooth, prominently carunculate.

Ivesia tweedyi

Ivesia paniculata
Phenology Flowering summer. Flowering summer.
Habitat Dry, gravelly to rocky flats, slopes, alpine ridges, often on serpentine, in subalpine conifer woodlands Dry shallow volcanic ash and cinders atop volcanic bedrock, open sagebrush communities, adjacent conifer woodlands
Elevation 1600–2300 m (5200–7500 ft) 1500–1800 m (4900–5900 ft)
Distribution
from FNA
ID; MT; WA
[WildflowerSearch map]
[BONAP county map]
from FNA
CA
[BONAP county map]
Discussion

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.)

Of conservation concern.

Ivesia paniculata is known only from the Ash Valley area of Lassen County. The distinctions between I. paniculata and I. rhypara are perhaps on the same scale as variation among disjunct population clusters of I. rhypara, but no taxonomic adjustments are proposed at this time.

(Discussion copyrighted by Flora of North America; reprinted with permission.)
Source FNA vol. 9, p. 235. FNA vol. 9, p. 229.
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. 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. 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
Synonyms Potentilla tweedyi
Name authority Rydberg: in N. L. Britton et al., N. Amer. Fl. 22: 288. (1908) T. W. Nelson & J. P. Nelson: Brittonia 33: 165, fig. 1. (1981)
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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