Flora of North America species comparison

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Ivesia argyrocoma var. argyrocoma

Ivesia sect. Unguiculatae
Photo is of parent taxon

silver-hair ivesia
Habit Plants silvery; glands obscured. Plants usually rosetted or tufted, rarely ± matted (I. kingii var. eremica), not forming hanging clumps, not aromatic; taproot stout to fusiform and fleshy.
Stems

prostrate to ascending, (0.3–)1–2.5(–3) dm.

(0.3–)1–4.5(–5.5) dm.
Basal leaves

4–8(–10) cm; sheathing base sparsely to densely strigose abaxially;

stipules lanceolate, 1–2 mm;

petiole (0.5–)1–3 cm, hairs abundant, spreading, (1–)3–5 mm;

leaflets 25–35 per side, tightly overlapping, (1–)2–3.5 mm, lobes 2–3, elliptic to obovate or oval, hairs dense, appressed to ascending, 0.5–1.5 mm.

loosely to tightly cylindric (± mousetail-like in I. argyrocoma and I. kingii var. eremica);

stipules present or absent;

leaflets loosely or, sometimes, tightly overlapping, individually distinguishable or not, lobed to base, sometimes entire;

terminal leaflets indistinct, sparsely to densely hairy or glabrate.
Cauline leaves

(1–)2–3.

(1–)2–10(–15), not paired;

blade ± well developed.
Inflorescences

(5–)10–30-flowered, (1–)1.5–4(–6) cm diam., flowers arranged in 1–several ± tight glomerules of 10–20(–30) flowers.

open to congested, flowers arranged individually and/or in glomerules, these usually ± capitate.
Pedicels

1–3 mm.

remaining ± straight (rarely ± curved in I. argyrocoma).
Flowers

7–9 mm diam.;

epicalyx bractlets mostly linear to narrowly ovate, 0.8–2(–2.5) mm;

hypanthium cupulate, (1–)1.5–2 × (2–)2.5–3(–3.5) mm, 1/2–2/3 as deep as wide;

sepals sometimes purple-suffused, 2–3(–4) mm, acute;

petals white, obovate, (2–)3–4(–4.5) mm;

stamens 20, filaments flattened, 0.6–1.3 mm, anthers yellowish, 0.3–0.5 mm;

carpels 4–8, styles 1.5–2.2 mm.

hypanthium shallowly cupulate or campanulate to turbinate, rarely patelliform (I. pityocharis);

petals not medially reflexed, light yellow to white, sometimes pink-tinged, ± clawed, apices rounded or truncate to emarginate;

stamens usually 20 (10–15 in I. unguiculata, 12–20 in I. campestris), anthers ± as long as to longer than wide, laterally dehiscent;

carpels (1–)2–20.
Achenes

brown, (1.5–)2–2.5 mm.

vertical, smooth, not carunculate.

Ivesia argyrocoma var. argyrocoma

Ivesia sect. Unguiculatae
Phenology Flowering summer.
Habitat Dry meadows, gravelly soil, in montane conifer woodlands
Elevation 1400–2300 m (4600–7500 ft)
Distribution
from FNA
CA
w United States; nw Mexico
Discussion

Of conservation concern.

Variety argyrocoma is found only on so-called pebble plains in the eastern San Bernardino Mountains, San Bernardino County. The filaments are significantly more flattened than those of other species of Ivesia and approach those that characterize Horkelia.

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

Species 8 (8 in the flora).

Section Unguiculatae encompasses a series of species that have radiated in montane meadows in California, from Siskiyou and Trinity counties through the Sierra Nevada to the San Bernardino Mountains, and in the Carson, Virginia, and Pine Nut ranges in adjacent Nevada; one variety of Ivesia argyrocoma is endemic to the Sierra San Pedro Mártir in Baja California, Mexico. The species occur in seasonally wet/dry meadows and flats, including some specific substrate types of localized occurrence that often support suites of endemic species. The most widespread species in the section, I. kingii, has adapted to alkali-crusted valley bottoms extending across the Great Basin to western Utah.

Members of sect. Unguiculatae are nearly glabrous to densely sericeous but lack the conspicuous glandularity and distinctive ivesioid smell that characterize sects. Ivesia and Setosae. The taproot is often elongate and fleshy-thickened, which is apparently an adaption for when the preferred habitat becomes seasonally desiccated. Leaves are cylindric with deeply lobed leaflets. Flowers are usually aggregated into multiple few- to many-flowered glomerules; sometimes they are individually arranged in diffuse inflorescences. Petals are white to pale yellow but never golden yellow and are often conspicuously clawed. Stamens are commonly 20 except in Ivesia campestris and I. unguiculata.

(Discussion copyrighted by Flora of North America; reprinted with permission.)
Key
1. Filaments flattened; leaflets (1–)2–3.5 mm, tightly overlapping; plants silvery; stems prostrate to ascending, (0.3–)1–2.5(–3) dm; cauline leaves (1–)2–3; San Bernardino Mountains, s California.
I. argyrocoma
1. Filaments filiform; leaflets (1.5–)2–15(–20) mm, loosely overlapping (tightly so in some I. kingii); plants green to grayish or silvery; stems prostrate-decumbent to erect, (0.5–)1–4(–5.5) dm; cauline leaves 2–15; w United States
→ 2
2. Stamens 10–20, filaments 0.6–1.1 mm; leaflets 15–20(–25) per side; c, s Sierra Nevada, California
→ 3
2. Stamens 20, filaments (1–)1.5–4 mm; leaflets 15–50(–60) per side; n California to Utah
→ 4
3. Petals 5, white, often tinged with pink; sepals heavily purple-mottled; inflorescences (15–)30–100(–200)-flowered; c Sierra Nevada.
I. unguiculata
3. Petals 4(–5), light yellow; sepals green; inflorescences 5–20(–40)-flowered; s Sierra Nevada.
I. campestris
4. Flowers arranged in tight glomerules of 5–20 flowers; pedicels 1–3(–15) mm
→ 5
4. Flowers arranged individually or in loose glomerules of 2–10 flowers; pedicels (1–)2–20(–25) mm
→ 6
5. Petals white; petiole hairs usually spreading, 1–4 mm; hypanthia campanulate to shallowly turbinate, 1.5–3 mm, often nearly as deep as wide.
I. sericoleuca
5. Petals light yellow; petiole hairs ascending, ± 1(–3) mm; hypanthia cupulate, 1–2 mm, 1/2–2/3 as deep as wide.
I. aperta
6. Petals oblanceolate to narrowly spatulate; hypanthia cupulate to turbinate, 1.5–3 mm, often nearly as deep as wide; on ultramafic-derived soil; n California.
I. pickeringii
6. Petals spatulate or obovate to orbiculate; hypanthia shallowly cupulate to patelliform, 0.5–2.5 mm, ± 1/2 as deep as wide; on alkaline soil or in non-alkaline meadows; Great Basin and n Mojave Desert
→ 7
7. Leaflets 15–60 per side, hairs absent or 0.2–0.5(–1) mm, ± appressed; carpels 2–9; alkali-crusted flats, e California, Nevada, sw Utah.
I. kingii
7. Leaflets 5–25 per side, hairs 1–3 mm, spreading to ascending; carpels 8–20; meadows in sagebrush, Pine Nut Mountains, Nevada.
I. pityocharis
Source FNA vol. 9, p. 242. FNA vol. 9, p. 237.
Parent taxa Rosaceae > subfam. Rosoideae > tribe Potentilleae > Ivesia > sect. Unguiculatae > Ivesia argyrocoma Rosaceae > subfam. Rosoideae > tribe Potentilleae > Ivesia
Subordinate taxa
I. aperta, I. argyrocoma, I. campestris, I. kingii, I. pickeringii, I. pityocharis, I. sericoleuca, I. unguiculata
Synonyms Horkelia unranked Unguiculatae, Horkelia unranked Eremicae, I. unranked Eremicae, I. section Eremicae, I. unranked Unguiculatae
Name authority unknown (Rydberg) O. Stevens: in N. L. Britton et al., N. Amer. Fl. 22(7): 8. (1959)
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Unless otherwise noted, all data comes from the online version of the Flora of North America, who have made most of their content available via a Creative Commons license (CC BY 4.0).



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