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Pickering's ivesia, silky mousetail

rock ivesia, rock mousetail

Habit Plants grayish green; glands abundant. Plants green, ± tufted, often forming hanging clumps, sometimes rosetted.
Stems

ascending to erect, 3–5 dm.

pendent or prostrate to ascending, 0.4–2.6(–3) dm.

Basal leaves

8–20 cm; sheathing base ± strigose abaxially;

stipules linear to narrowly lanceolate, 3–5 mm;

petiole 1–3.5 cm, hairs abundant, ascending to spreading, 1–2 mm;

leaflets 35–50 per side, loosely overlapping, 2–6 mm, lobes 3–5, oblanceolate to obovate or oval, hairs abundant, ± ascending, 1–2(–3) mm.

planar, 2–15 cm; sheathing base not strigose abaxially;

petiole 3–9 cm;

lateral leaflets (1–)2–4(–7) per side, separate to slightly overlapping, obovate to orbiculate or flabellate, (3–)5–15(–22) mm, incised 1/4–3/4 to base into 5–15 broadly ovate teeth or oblanceolate lobes, sometimes also medially split to base (Kern Plateau), apex not setose, surfaces ± sparsely short-pilose, prominently glandular;

terminal leaflets ± distinct.

Cauline leaves

5–10.

1–2(–4);

blade well developed.

Inflorescences

10–100-flowered, (1.5–)5–15 cm diam., flowers usually arranged individually, sometimes more congested.

(1–)3–30(–60)-flowered, open, (0.5–)2–8 cm diam.

Pedicels

(1–)2–10 mm.

(5–)10–30 mm.

Flowers

8–13 mm diam.;

epicalyx bractlets linear-lanceolate to lanceolate, (1.8–)2–2.5 mm;

hypanthium cupulate to turbinate, 1.5–3 × 2.5–4 mm, often nearly as deep as wide;

sepals often purple-suffused or -mottled, (2.5–)3–5 mm, acuminate;

petals white, becoming pink-tinged with age, oblanceolate to narrowly spatulate, (2.8–)3–5(–6) mm;

stamens 20, filaments filiform, 1.5–2.3 mm, anthers white to cream, 0.3–0.6 mm;

carpels 2–4, styles 2.5–3.5 mm.

6–12 mm diam.;

epicalyx bractlets 5, broadly lanceolate to oblong, 1–2.5 mm;

hypanthium patelliform, 0.5–1.5 × 2–4(–4.5) mm;

sepals 2–4.5 mm, acute;

petals yellow, oblanceolate to obovate, (1.5–)2–4 mm;

stamens 15–35(–40), filaments 0.3–1 mm, anthers yellow, subrotund, 0.2–0.3(–0.5) mm;

carpels (3–)10–20(–40), styles 1–2 mm.

Achenes

dark brown, 2.5–3 mm.

greenish white to light tan, 1–1.8 mm, faintly rugose, ± carunculate.

Ivesia pickeringii

Ivesia saxosa

Phenology Flowering summer. Flowering late spring–summer.
Habitat Moist, rocky, grassy meadows, mainly on ultramafic-derived clayey soil, in montane conifer woodlands Dry, rocky outcrops of granitic or volcanic origin, usually crevices of more or less vertical protected cliffs or boulders, mainly in oak and conifer woodlands
Elevation 800–1500 m (2600–4900 ft) 900–3300 m (3000–10800 ft)
Distribution
from FNA
CA
[BONAP county map]
from FNA
CA; Mexico (Baja California)
[WildflowerSearch map]
[BONAP county map]
Discussion

Of conservation concern.

Ivesia pickeringii is known from Siskiyou and Trinity counties. Some early treatments (for example, P. A. Rydberg 1898, 1908–1918; W. L. Jepson [1923–1925], 1909–1943, vol. 2) conflated this species with I. aperta, hence reports of I. pickeringii in the Sierra Nevada. Historic collections from Edgewood, at the headwaters of the Shasta River in Siskiyou County, have inflorescences more glomerulate than elsewhere in the species range.

The chromosome count of 2n = 28 (P. A. Munz 1959) needs confirmation. If based on Kruckeberg 3665, which was distributed as a voucher for that count, the determination of this collection has been changed to Ivesia sericoleuca.

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

Ivesia saxosa is encountered in the foothills and mountains of southeastern California from the White Mountains and adjacent eastern slopes of the Sierra Nevada of Mono County to the Transverse Ranges (including the Little San Bernardino Mountains) of Kern and San Bernardino counties. Populations on the Kern Plateau tend to have more dissected leaflets and may deserve recognition as a distinct variety. On the Peninsular Ranges, I. saxosa occurs in Riverside and San Diego counties and into northern Baja California, Mexico, as far south as the western slopes of the Sierra Juárez and Sierra San Pedro Mártir.

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

Source FNA vol. 9, p. 239. FNA vol. 9, p. 223.
Parent taxa Rosaceae > subfam. Rosoideae > tribe Potentilleae > Ivesia > sect. Unguiculatae 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. 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. sericoleuca, I. setosa, I. shockleyi, I. tweedyi, I. unguiculata, I. utahensis, I. webberi
Synonyms Potentilla pickeringii Potentilla saxosa, P. acuminata, P. saxosa subsp. sierrae
Name authority Torrey ex A. Gray: Proc. Amer. Acad. Arts 6: 531. (1865) (Lemmon ex Greene) Ertter: Syst. Bot. 14: 232. (1989)
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