Hickman’s cinquefoil

Plants ± rosetted; taproots fleshy-thickened. Stems usually prostrate to decumbent, sometimes ± ascending in supporting vegetation, 0.5–2.5 dm, lengths 1–2 times basal leaves. Basal leaves pinnate with distal leaflets ± confluent, 3–17 × 1–3.5 cm; petiole 1–5 cm, straight hairs sparse to common, appressed, 0.5–1.5(–2) mm, stiff, cottony hairs absent, glands absent or sparse; primary lateral leaflets 3–6 per side, on distal 1/2–2/3 of leaf axis, ± overlapping to nearly separate, largest ones cuneate to flabellate, 0.5–2 × 0.5–1.5 cm, distal 1/2 to whole margin ± palmately incised 1/2–2/3(+) to midvein, ultimate teeth or segments 2–5, narrowly elliptic to oblanceolate, 2–10(–15) × (1–)1.5–3 mm, apical tufts 0.5 mm, surfaces green, not glaucous, straight hairs sparse to common (often sparser to glabrate adaxially), appressed, 1–1.5 mm, stiff, cottony hairs absent, glands absent or inconspicuous. Cauline leaves 2. Inflorescences 2–5-flowered, very openly cymose, sometimes racemiform. Pedicels 1–2(–4) cm, ± recurved in fruit. Flowers: epicalyx bractlets ± elliptic, 3.5–6 × (1–)1.5–2.5 mm; hypanthium 3–5 mm diam.; sepals 3.5–7(–9) mm, apex acute; petals 6–12 × 5–9 mm; filaments (1.5–)2–3(–4) mm, anthers 0.7–1.2 mm; carpels (2–)5–15, styles 2.5–3.5 mm. Achenes 2 mm, smooth, ± carunculate.

Flowering spring–early summer. Vernally saturated coastal meadows, openings in Monterey Pine forests; of conservation concern; 30–100 m; Calif.

Potentilla hickmanii is known from only two extant populations in Monterey and San Mateo counties. The species is a federally listed endangered species (U.S. Fish and Wildlife Service, ecos.fws.gov/docs/recovery_plan/050617a.pdf). Plants from Sonoma County formerly included in P. hickmanii now constitute P. uliginosa. Although some morphologic overlap occurs with P. millefolia, P. hickmanii generally differs in having less dissected leaflets occupying less of the leaf axis, as well as somewhat larger flowers bearing fewer carpels.