Horkelia Chamisso & Schlechtendal [unranked] Unguiculatae Rydberg, Monogr. N. Amer. Potentilleae, 124. 1898; Horkelia [unranked] Eremicae Rydberg; Ivesia [unranked] Eremicae (Rydberg) Rydberg; Ivesia sect. Eremicae (Rydberg) O. Stevens; Ivesia [unranked] Unguiculatae (Rydberg) Rydberg

Plants usually rosetted or tufted, rarely ± matted (I. kingii var. eremica), not forming hanging clumps, not aromatic; taproot stout to fusiform and fleshy. Stems (0.3–)1–4.5(–5.5) dm. Basal leaves 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–)2–10(–15), not paired; blade ± well developed. Inflorescences open to congested, flowers arranged individually and/or in glomerules, these usually ± capitate. Pedicels remaining ± straight (rarely ± curved in I. argyrocoma). Flowers: 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 vertical, smooth, not carunculate.

Species 8 (8 in the flora): w United States, nw Mexico.

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.