Utah ivesia

Potentilla utahensis (S. Watson) Greene

Plants green, rosetted to tufted; taproot proximally enlarged, not fleshy. Stems prostrate to ascending, 0.5–1.5(–2) dm. Basal leaves ± tightly cylindric, 2–7(–9) cm; sheathing base glabrous abaxially; petiole 0.5–2 cm, hairs 0.5–1 mm; leaflets 15–20 per side, 2–4 mm, glabrate or sparsely short-hirsute, sparsely to densely glandular, lobes (2–)3–8, narrowly oblanceolate to obovate, apex not setose. Cauline leaves (0–)1, not paired. Inflorescences (5–)10–30-flowered, 1–2.5(–5) cm diam.; glomerules 1–few. Pedicels 1–7 mm. Flowers 7–9 mm diam.; epicalyx bractlets narrowly oblong to oval, 0.8–2 mm; hypanthium shallowly cupulate, (1–)1.5–2 × 2.5–3.5 mm; sepals (1.8–)2–3 mm, acute; petals white, sometimes pink-tinged, oblanceolate to spatulate, 1.8–3 mm; stamens 5, filaments 1.3–1.8 mm, anthers orangish to reddish brown, 0.4–0.6 mm; carpels (1–)2–4, styles 1.5–2 mm. Achenes yellowish green to light tan or gray-brown, 1.7–1.9 mm.

Flowering summer. Talus slopes, bare ridges, in high-elevation sagebrush communities, subalpine to alpine conifer woodlands; of conservation concern; 3200–3700 m; Utah.

Ivesia utahensis is known from the Wasatch and adjacent Uinta Mountains in northern Utah. The species stands as the white-petaled counterpart to the yellow-petaled Sierran I. lycopodioides, possibly indicating a common ancestral stock that was once more continuous across the Great Basin.