Ivesia paniculata |
Ivesia saxosa |
|
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Ash Creek ivesia, Ash Creek mousetail |
rock ivesia, rock mousetail |
|
Habit | Plants grayish, ± matted. | Plants green, ± tufted, often forming hanging clumps, sometimes rosetted. |
Stems | ± prostrate, 0.4–1.5(–2) dm. |
pendent or prostrate to ascending, 0.4–2.6(–3) dm. |
Basal leaves | 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. |
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 | (0–)1; blade reduced. |
1–2(–4); blade well developed. |
Inflorescences | 20–200-flowered, congested, (1–)1.5–6(–10) cm diam. |
(1–)3–30(–60)-flowered, open, (0.5–)2–8 cm diam. |
Pedicels | 1.5–6 mm. |
(5–)10–30 mm. |
Flowers | 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. |
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 | brown, 0.8–1.5 mm, smooth, prominently carunculate. |
greenish white to light tan, 1–1.8 mm, faintly rugose, ± carunculate. |
Ivesia paniculata |
Ivesia saxosa |
|
Phenology | Flowering summer. | Flowering late spring–summer. |
Habitat | Dry shallow volcanic ash and cinders atop volcanic bedrock, open sagebrush communities, adjacent 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 | 1500–1800 m (4900–5900 ft) | 900–3300 m (3000–10800 ft) |
Distribution |
CA |
CA; Mexico (Baja California)
|
Discussion | 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.) |
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. 229. | FNA vol. 9, p. 223. |
Parent taxa | ||
Sibling taxa | ||
Synonyms | Potentilla saxosa, P. acuminata, P. saxosa subsp. sierrae | |
Name authority | T. W. Nelson & J. P. Nelson: Brittonia 33: 165, fig. 1. (1981) | (Lemmon ex Greene) Ertter: Syst. Bot. 14: 232. (1989) |
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