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Pickering's ivesia, silky mousetail

Charleston Peak ivesia, Charleston Peak mousetail

Habit Plants grayish green; glands abundant. Plants green, diffusely matted.
Stems

ascending to erect, 3–5 dm.

prostrate to decumbent, 0.2–0.6(–1) 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.

tightly cylindric, 1–4(–5) cm; sheathing base mostly not strigose abaxially;

petiole 0.3–2 cm, hairs 0.5–1 mm;

lateral leaflets 5–10(–12) per side, ± overlapping, ± flabellate, 1–2.5 mm, incised to base or nearly so into 3–5 obovate to oval lobes, apex sometimes ± setose, surfaces loosely long-strigose, sparsely glandular;

terminal leaflets indistinct.

Cauline leaves

5–10.

1(–2);

blade vestigial.

Inflorescences

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

1–10-flowered, ± congested, 0.5–1.5 cm diam.

Pedicels

(1–)2–10 mm.

3–7(–10) 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.

6–9 mm diam.;

epicalyx bractlets 5, lanceolate to narrowly oblong or narrowly ovate, 0.8–1.3 mm;

hypanthium shallowly cupulate, ± 1 × 2–3(–4) mm;

sepals 1.5–2.3 mm, ± acute;

petals yellow, oblanceolate to spatulate, 2–3.2 mm;

stamens 5, filaments 0.9–1.2 mm, anthers yellow, oblong, 0.7–0.9 mm;

carpels 6–10, styles 1–1.5 mm.

Achenes

dark brown, 2.5–3 mm.

greenish cream to light brown, 1.4–1.8(–2) mm, smooth, not carunculate.

Ivesia pickeringii

Ivesia cryptocaulis

Phenology Flowering summer. Flowering summer.
Habitat Moist, rocky, grassy meadows, mainly on ultramafic-derived clayey soil, in montane conifer woodlands Dry to moist limestone gravel, scree, or talus slopes and outcrops, subalpine conifer woodlands, alpine tundra communities
Elevation 800–1500 m (2600–4900 ft) 2500–3700 m (8200–12100 ft)
Distribution
from FNA
CA
[BONAP county map]
from FNA
NV
[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.)

Of conservation concern.

Ivesia cryptocaulis is known only from timberline and above in the Spring Mountains of Clark County. Plants differ from all others of the genus by having slender, elongate, diffuse caudex branches that ramify through its habitat of gravel, scree, and talus. The species is here provisionally included in sect. Setosae as a diffusely matted relative of I. shockleyi (as also suggested by D. D. Keck 1938); the ecarunculate seeds and relatively straight pedicels may indicate a greater similarity to I. pygmaea in sect. Ivesia.

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

Source FNA vol. 9, p. 239. FNA vol. 9, p. 228.
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. 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
Synonyms Potentilla pickeringii Potentilla cryptocaulis
Name authority Torrey ex A. Gray: Proc. Amer. Acad. Arts 6: 531. (1865) (Clokey) D. D. Keck: Lloydia 1: 130. (1939)
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