Flora of North America species comparison

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Ivesia tweedyi

Ivesia webberi

Tweedy's ivesia, Tweedy's mousetail

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

ascending to erect, 0.4–2(–3.5) dm.

decumbent to ascending, 0.5–1.5(–1.8) 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.

loosely ± cylindric, 3–7(–10) cm; sheathing base ± strigose abaxially;

petiole 0.5–5(–6) cm, hairs 2–4 mm;

leaflets 4–8(–10) per side, (0.5–)3–8(–10) mm, loosely long-strigose or -villous and short-hirsute, ± glandular, lobes 2–5(–12), linear to lanceolate, apex not setose.
Cauline leaves

(0–)1–2, not paired.

2, paired.
Inflorescences

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

glomerules 1–few.

5–15(–25)-flowered, 1.5–3(–6) cm diam.;

glomerules 1.
Pedicels

1–3(–5) mm.

(0.5–)1–8(–13) 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.

9–12 mm diam.;

epicalyx bractlets linear, 1.2–3 mm;

hypanthium cupulate, 1–2(–2.5) × 2.5–5 mm;

sepals 2.5–4.5(–5.5) mm, acute;

petals yellow, narrowly oblanceolate, 2–3(–4) mm;

stamens 5, filaments 1.8–2.5(–3) mm, anthers yellow, (0.8–)1–1.6 mm;

carpels 3–8, styles 1.8–2.2 mm.
Achenes

olive green, 1.8–2 mm.

light brown, often mottled darker brown, 1.9–2.5 mm.

Ivesia tweedyi

Ivesia webberi
Phenology Flowering summer. Flowering late spring–early summer.
Habitat Dry, gravelly to rocky flats, slopes, alpine ridges, often on serpentine, in subalpine conifer woodlands Dry flats and slopes, in sagebrush communities, conifer woodlands
Elevation 1600–2300 m (5200–7500 ft) (1300–)1500–1900 m ((4300–)4900–6200 ft)
Distribution
from FNA
ID; MT; WA
[WildflowerSearch map]
[BONAP county map]
from FNA
CA; NV
[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 webberi is known only from the eastern foothills of the northern Sierra Nevada and scattered ranges to the east in California and adjacent Nevada. It is among the more distinctive species in the genus and is only tentatively placed in sect. Ivesia. The leaflets are loosely incised into slender, sparsely villous segments, and the two cauline leaves are paired with dissected stipules. Previous reports of the stems and inflorescence branches being glandular-puberulent are due to a misinterpretation of the minute pustulose bases associated with the villous indumentum as being enlarged glands.

(Discussion copyrighted by Flora of North America; reprinted with permission.)
Source FNA vol. 9, p. 235. FNA vol. 9, p. 236.
Parent taxa Rosaceae > subfam. Rosoideae > tribe Potentilleae > Ivesia > sect. Ivesia Rosaceae > subfam. Rosoideae > tribe Potentilleae > Ivesia > sect. Ivesia
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. 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
Synonyms Potentilla tweedyi Potentilla webberi
Name authority Rydberg: in N. L. Britton et al., N. Amer. Fl. 22: 288. (1908) A. Gray: Proc. Amer. Acad. Arts 10: 71. (1874)
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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