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Ash Creek ivesia, Ash Creek mousetail

Habit Plants grayish, ± matted.
Stems

± prostrate, 0.4–1.5(–2) 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.

Cauline leaves

(0–)1;

blade reduced.

Inflorescences

20–200-flowered, congested, (1–)1.5–6(–10) cm diam.

Pedicels

1.5–6 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.

Achenes

brown, 0.8–1.5 mm, smooth, prominently carunculate.

Ivesia paniculata

Phenology Flowering summer.
Habitat Dry shallow volcanic ash and cinders atop volcanic bedrock, open sagebrush communities, adjacent conifer woodlands
Elevation 1500–1800 m (4900–5900 ft)
Distribution
from FNA
CA
[BONAP county map]
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.)

Source FNA vol. 9, p. 229.
Parent taxa 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. 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
Name authority T. W. Nelson & J. P. Nelson: Brittonia 33: 165, fig. 1. (1981)
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