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rock ivesia, rock mousetail

Habit Plants green, ± tufted, often forming hanging clumps, sometimes rosetted. Herbs, perennial, rarely annual or biennial, shrubs, or subshrubs; unarmed.
Stems

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

Leaves

alternate, rarely opposite, pinnately (palmately) compound (simple in Alchemilla, Aphanes, and Chamaerhodos);

stipules persistent (absent in Chamaerhodos), adnate to petiole;

venation pinnate or palmate.

Basal leaves

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

1–2(–4);

blade well developed.

Inflorescences

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

Pedicels

(5–)10–30 mm.

Flowers

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.

perianth and androecium perigynous;

epicalyx bractlets present, sometimes absent;

hypanthium usually patelliform, cupulate, or campanulate, sometimes turbinate, saucer-shaped, flat-bottomed, or subglobose to ellipsoid or ovoid;

torus flat to conic or turbinate, enlarged (absent or reduced in Alchemilla, Aphanes, and Chamaerhodos);

carpels 1–260, styles basal or lateral to subterminal, distinct;

ovules 1(or 2), basal.

Fruits

aggregated achenes (achenes in Alchemilla and Aphanes);

torus sometimes fleshy;

styles deciduous or persistent, not elongate.

Achenes

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

Ivesia saxosa

Rosaceae tribe Potentilleae

Phenology Flowering late spring–summer.
Habitat 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 900–3300 m (3000–10800 ft)
Distribution
from FNA
CA; Mexico (Baja California)
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[BONAP county map]
North America; Mexico; Central America; South America; West Indies; Bermuda; Eurasia; Africa; Atlantic Islands; Pacific Islands; Australia
Discussion

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.)

Genera 14–22, species ca. 860 (14 genera, 189 species, including 1 hybrid, in the flora area).

The base chromosome number for Potentilleae is mostly x = 7 (8 in Alchemilla and Aphanes; 14 in Comarum).

Variation in the number of genera recognized in Potentilleae is due to differences in generic delimitation between D. Potter et al. (2007) and the authors of Potentilla and segregates here (see 9. Ivesia and 8. Potentilla for discussion). In the former, Duchesnea, Horkelia, Horkeliella, and Ivesia are included within Potentilla. Likewise, Aphanes is included within Alchemilla by Potter et al. while it is kept distinct here.

Potentilla and its segregates and Fragaria are host to Phragmidium rusts, but not the other genera of the tribe.

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

Key
1. Shrubs; leaf lobe margins entire; achenes hirsute.
Dasiphora
1. Herbs, perennial, sometimes annual or biennial, or subshrubs; leaf lobe margins or apices ± toothed, sometimes entire; achenes glabrous (sometimes ± hairy)
→ 2
2. Petals 0, sepals 4; achenes 1, enclosed in dry, urceolate or subglobose to ellipsoid or ovoid hypanthia
→ 3
2. Petals and sepals usually 5; achenes 1–260, usually aggregated (sometimes on elongating tori), usually in (± open) patelliform, cupulate, campanulate, or turbinate hypanthia (not enclosed in dry hypanthium)
→ 4
3. Herbs perennial; leaves basal, blades reniform to orbiculate, palmately lobed, sometimes palmately compound; stamens 4.
Alchemilla
3. Herbs annual; leaves cauline, blades cuneate, deeply divided into segments, each lobed; stamen 1(or 2).
Aphanes
4. Leaves all or mostly basal or proximal (if cauline, deeply pinnatifid), ternate or 2–4-ternate (sometimes simple and coarsely toothed apically in Sibbaldia)
→ 5
4. Leaves basal or cauline, the latter usually reduced distally, odd-pinnate to palmate, rarely ternate or ± bipinnate
→ 9
5. Tori becoming red and fleshy in fruit; leaf margins serrate to crenate
→ 6
5. Tori hemispheric (not enlarged or fleshy) in fruit or absent; leaf margins entire or (2–)3(–5)-toothed apically
→ 7
6. Leaves ± doubly serrate or crenate; stolons leafy; inflorescences: flowers solitary, axillary at stolon nodes; petals yellow.
Duchesnea
6. Leaves serrate to crenate; stolons not leafy; inflorescences 1–10-flowered, cymes, axillary from leaf rosettes; petals usually white.
Fragaria
7. Leaves pinnately compound or simple and deeply pinnatifid, margins entire, stipules absent.
Chamaerhodos
7. Leaves ternate, margins toothed apically, stipules persistent
→ 8
8. Petals ± yellow; stamens 5.
Sibbaldia
8. Petals usually white; stamens 20(–30).
Sibbaldiopsis
9. Petals deep red to purple, rarely pink, shorter than sepals; tori enlarged and spongy at maturity; horizontal stems sometimes floating, wetland habitats.
Comarum
9. Petals yellow to white, rarely pink or red (then equal to or longer than sepals); tori not enlarged and spongy at maturity; stems erect to decumbent, not horizontal or floating even if in wetlands
→ 10
10. Anthers dehiscing by continuous marginal slit (with a single theca); styles sub-basal.
Drymocallis
10. Anthers dehiscing longitudinally; styles subterminal to lateral
→ 11
11. Hypanthium patelliform to campanulate or cupulate to turbinate (not flat-bottomed); filaments not forming tube; petals white to yellow, sometimes reddish or pink tinged
→ 12
11. Hypanthium ± cupulate or bluntly campanulate and flat-bottomed; filaments forming tube; petals usually white, sometimes pink-tinged, rose-veined, or cream
→ 13
12. Plants not aromatic; leaves ± cordate or reniform to narrowly elliptic in outline, leaflets 3–15(–41); petals oblanceolate or obovate to obcordate to nearly round, rarely elliptic; carpels 3–260.
Potentilla
12. Plants often aromatic; leaves planar to cylindric, leaflets (3–)7–161; petals linear or narrowly oblanceolate to obovate, sometimes obcordate; carpels 1–20(–40).
Ivesia
13. Stamens 10; leaflets (3–)5–41.
Horkelia
13. Stamens 20; leaflets 30–70.
Horkeliella
Source FNA vol. 9, p. 223. FNA vol. 9, p. 119. Author: Luc Brouillet.
Parent taxa Rosaceae > subfam. Rosoideae > tribe Potentilleae > Ivesia > sect. Setosae Rosaceae > subfam. Rosoideae
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. 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
Subordinate taxa
Alchemilla, Aphanes, Chamaerhodos, Comarum, Dasiphora, Drymocallis, Duchesnea, Fragaria, Horkelia, Horkeliella, Ivesia, Potentilla, Sibbaldia, Sibbaldiopsis
Synonyms Potentilla saxosa, P. acuminata, P. saxosa subsp. sierrae
Name authority (Lemmon ex Greene) Ertter: Syst. Bot. 14: 232. (1989) Sweet: Brit. Fl. Gard. 2: sub plate 124. (1825)
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