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silver-hair ivesia, silverhair mousetail

Ivesia longibracteata

Castle Crags ivesia, longbract mousetail

Habit Plants green, ± tufted; taproot ± stout, not fleshy.
Stems

ascending to erect, 0.3–1.2 dm.

Basal leaves

weakly planar to loosely ± cylindric, (0.5–)2–4(–6) cm; sheathing base glandular abaxially, otherwise glabrous;

petiole 0.5–2 cm, hairs 0.2–1 mm;

leaflets 5–6 per side, 2–6 mm, ± short-hirsute, glandular-puberulent, lobes 2–7, oblanceolate to spatulate or obovate, apex not setose.

Cauline leaves

1–3, not paired.

Inflorescences

3–14-flowered, 1–2.5 cm diam.;

glomerules 1.

Pedicels

1.5–6 mm.

Flowers

8–10 mm diam.;

epicalyx bractlets linear to narrowly lanceolate or elliptic, 2.5–5 mm, longer than sepals;

hypanthium shallowly cupulate, 0.5–1 × 2–3 mm;

sepals 1.5–2.5 mm, ± acute;

petals pale yellow, linear to narrowly oblanceolate, 1.5–2.5 mm;

stamens 5, filaments 0.7–1.3 mm, anthers yellow, 0.5–0.8 mm;

carpels 6–11, styles 1–1.5 mm.

Achenes

cream to light tan, 1.2–1.5 mm.

Ivesia argyrocoma

Ivesia longibracteata

Phenology Flowering summer.
Habitat Dry crevices of granodioritic igneous rock, in mixed oak-conifer woodlands
Elevation 1200–1400 m (3900–4600 ft)
Distribution
from FNA
CA; nw Mexico
[WildflowerSearch map]
[BONAP county map]
from FNA
CA
[BONAP county map]
Discussion

Varieties 2 (1 in the flora).

Plants from the central Sierra San Pedro Mártir in northern Baja California belong to var. moranii Ertter & Reveal, which may be distinguished by its compact stature (to 0.5 dm), densely villous basal stipules 2–4 mm, decumbent stems 2–7 cm that are stipitate-glandular under the villous indumentum, and solitary, loosely congested cyme. The petals are oblanceolate to narrowly obovate and 2.5–3.5 mm. The grayish, faintly mottled achenes are 1.3–2 mm.

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

Of conservation concern.

Ivesia longibracteata is known only from the Castle Crags area of Shasta County. The epithet alludes to a diagnostic characteristic unique in the genus: the epicalyx bractlets are longer than the sepals. The plants grow on vertical rock faces, a habitat more characteristic of sect. Setosae; however, the stems are ascending to erect and do not form hanging clumps, and the pedicels are not curved in fruit.

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

Source FNA vol. 9, p. 242. FNA vol. 9, p. 236.
Parent taxa Rosaceae > subfam. Rosoideae > tribe Potentilleae > Ivesia > sect. Unguiculatae Rosaceae > subfam. Rosoideae > tribe Potentilleae > Ivesia > sect. Ivesia
Sibling taxa
I. aperta, 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, I. webberi
I. aperta, I. argyrocoma, I. arizonica, I. baileyi, I. callida, I. campestris, I. cryptocaulis, I. gordonii, I. jaegeri, I. kingii, 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
Subordinate taxa
I. argyrocoma var. argyrocoma
Synonyms Horkelia argyrocoma, Potentilla argyrocoma
Name authority (Rydberg) Rydberg: in N. L. Britton et al., N. Amer. Fl. 22: 284. (1908) Ertter: Syst. Bot. 14: 233, fig. 1. (1989)
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