Potentilla arizonica

Plants rosetted to tufted; taproots ± fleshy-thickened. Stems decumbent to ascending, sometimes prostrate, 0.6–2.2 dm, lengths 1.5–3 times basal leaves. Basal leaves pinnate with distal leaflets ± distinct, 4–10 × 1–2(–3) cm; petiole 1–3 cm, straight hairs dense, ± appressed, 1–2 mm, stiff, cottony hairs absent, glands absent or sparse; primary lateral leaflets 5–7(–9) per side (sometimes with additional interspersed leaflets), on distal (1/2–)2/3–3/4 of leaf axis, ± overlapping, largest ones oblanceolate- to obovate-oblong, 0.5–1.5 × 0.4–0.8 cm, distal 3/4 to whole margin pinnately incised nearly to midvein, teeth (5–)7–9, linear-oblanceolate, 2–6 × 0.5–1 mm, apical tufts 1 mm, surfaces grayish green, straight hairs sparse (adaxially) to common, ± appressed, 1–2 mm, stiff, cottony hairs absent, glands absent or obscured. Cauline leaves (1–)2–3(–4). Inflorescences 3–15-flowered, ± compactly cymose, opening in fruit. Pedicels 0.7–2(–2.5) cm, straight in fruit. Flowers: epicalyx bractlets narrowly elliptic, sometimes doubled, 2–3.5 × 1–1.5 mm; hypanthium 3–4 mm diam.; sepals 4–6 mm, apex ± acute; petals 4–5(–6) × 3–4(–5.5) mm; filaments 1–2 mm, anthers 1–1.5 mm, often as long as filaments; carpels 8–20, styles 2 mm. Achenes 1.8 mm, ± smooth, not carunculate.

Phenology: Flowering late spring–early summer.
Habitat: Vernally wet clay of rocky basaltic meadows, openings in pine woodlands
Elevation: 1900–2100 m

Distribution

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Ariz.

Discussion

Of conservation concern.

Potentilla arizonica is known only from the Garland Prairie area in Coconino County. Although commonly included within P. plattensis (for example, N. H. Holmgren 1997b; B. C. Johnston 1980; T. H. Kearney and R. H. Peebles 1951), P. arizonica differs in its longer hairs, more erect habit, more condensed inflorescences, pedicels that remain straight in fruit, and significantly larger anthers.

Selected References

None.

Lower Taxa

None.