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Webber's ivesia, wire ivesia, wire mousetail

Habit Plants ± green, ± rosetted; taproot slender to ± stout, not fleshy. Herbs, shrubs, or subshrubs.
Stems

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

Leaves

alternate, rarely opposite, pinnately compound, sometimes simple or palmately compound;

stipules present, rarely absent.

Basal leaves

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

2, paired.

Inflorescences

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

glomerules 1.

Pedicels

(0.5–)1–8(–13) mm.

Flowers

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.

torus usually enlarged, sometimes small or absent;

carpels 1–260(–450), distinct, free, styles distinct, rarely connate (Roseae);

ovules 1(or 2), collateral (Rubeae) or superposed (Fallugia, Filipendula).

Fruits

achenes or aggregated achenes sometimes with fleshy, urn-shaped hypanthium or enlarged torus, sometimes aggregated drupelets;

styles persistent or deciduous, not elongate (elongate but not plumose in Geum).

Achenes

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

x

= 7(8).

Ivesia webberi

Rosaceae subfam. rosoideae

Phenology Flowering late spring–early summer.
Habitat Dry flats and slopes, in sagebrush communities, conifer woodlands
Elevation (1300–)1500–1900 m ((4300–)4900–6200 ft)
Distribution
from FNA
CA; NV
[BONAP county map]
North America; Mexico; Central America; South America; West Indies; Bermuda; Eurasia; Africa; Atlantic Islands; Indian Ocean Islands; Pacific Islands; Australia
Discussion

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.)

Variation in the number of genera in subfam. Rosoideae is due to differences in generic delimitation between D. Potter et al. (2007) and the authors of some Potentilleae genera. Cyanogenic glycosides and sorbitol are absent in the subfamily.

Tribes 6, genera 28–35, species ca. 1600 (6 tribes, 26 genera, 302 species, including 1 hybrid, in the flora)

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Source FNA vol. 9, p. 236. FNA vol. 9, p. 23. Author: Luc Brouillet.
Parent taxa Rosaceae > subfam. Rosoideae > tribe Potentilleae > Ivesia > sect. Ivesia Rosaceae
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. tweedyi, I. unguiculata, I. utahensis
Subordinate taxa
Synonyms Potentilla webberi
Name authority A. Gray: Proc. Amer. Acad. Arts 10: 71. (1874) Arnott: Botany, 107. (1832)
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