Ramona horkelia

Potentilla truncata (Rydberg) Jepson

Plants tufted, green. Stems erect, 2–6(–8) dm, hairs spreading. Basal leaves planar, 4–13 × 2–3.5(–4) cm; stipules entire or basally lobed; leaflets 1–3 per side, separate, oblong to obovate, 10–30 × 5–12(–15) mm, ± 1/2 as wide as long, divided 1/6–1/4 to midrib into (15–)20–30 acute to obtuse teeth, sparsely short-pilose to glabrate, especially adaxially. Cauline leaves 4–7. Inflorescences open, flowers arranged individually. Pedicels 4–20(–30) mm. Flowers 12–17 mm diam.; epicalyx bractlets broadly ovate, 3–4.5 × 2–3 mm, ± 2/3 length of sepals, entire; hypanthium 1.5–2 × 5–8 mm, less than 1/2 as deep as wide, interior glabrous; sepals ± reflexed, broadly ovate, 3.5–5.5 mm; petals obovate to round, 5–7 × (3–)4–7 mm, apex ± rounded; filaments 1–2 × 0.5–2 mm, anthers 0.8–1 mm; carpels 50–80; styles 1.5–3 mm. Achenes brown, 1.3–1.5 mm, smooth.

Flowering summer. Dry clay soil, in chaparral communities, oak woodlands; of conservation concern; 400–1300 m; Calif.; Mexico (Baja California).

Horkelia truncata is confined to the Peninsular Ranges of San Diego County, California, and northern Baja California, Mexico. Plants of the species are unusual in Horkelia in that the terminal leaflet is usually notably larger than the lateral leaflets, unlobed, and distinct, rather than confluent with the distal lateral ones.