Potentilla plattensis
Potentilla arizonica
Platte cinquefoil, Platte River cinquefoil
Garland prairie cinquefoil
initially decumbent to sometimes ascending, becoming prostrate or supported by vegetation, (0.3–)0.5–3.5(–4.5) dm, lengths 1.5–2.5(–4) times basal leaves.
decumbent to ascending, sometimes prostrate, 0.6–2.2 dm, lengths 1.5–3 times basal leaves.
pinnate with distal leaflets ± distinct, 2–15(–20) × 1–3 cm;
petiole 0.5–5 cm, straight hairs common, tightly appressed, 0.5(–1) mm, stiff, cottony hairs absent, glands absent or sparse;
primary lateral leaflets (3–)4–6(–8) per side, on distal (1/4–)1/2–3/4 of leaf axis, overlapping to separate, largest ones obovate, 0.5–1.5(–2) × 0.5–1(–1.3) cm, distal (1/2–)2/3 to whole margin pinnately incised 3/4+ to midvein, ultimate teeth 5–10, linear-oblanceolate, 1.5–8(–10) × 1–2 mm, apical tufts less than 0.5 mm, surfaces green to grayish green, not glaucous, straight hairs sparse to common (sparser adaxially), tightly appressed, 0.5 mm, stiff, cottony hairs absent, glands absent or inconspicuous.
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.
1–3.
(1–)2–3(–4).
(1–)3–15(–20)-flowered, loosely cymose, sometimes racemiform.
3–15-flowered, ± compactly cymose, opening in fruit.
1–4(–5) cm, ± recurved in fruit.
0.7–2(–2.5) cm, straight in fruit.
epicalyx bractlets narrowly elliptic to linear-lanceolate, 2–5(–6) × 0.5–2 mm;
hypanthium 3–4 mm diam.;
sepals 3–6 mm, apex acute;
petals 4–7 × 3–6 mm;
filaments 1–2.5 mm, anthers 0.5–1 mm, usually ± 1/2 as long as filaments;
carpels 10–20, styles 1.5–2.5 mm.
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.
(1.3–)1.5–1.9 mm, smooth, often ± carunculate.
1.8 mm, ± smooth, not carunculate.
= 70.
Potentilla plattensis
Potentilla arizonica
Potentilla plattensis occurs mostly east of the Continental Divide from the Canadian Prairies to the mountains of New Mexico. The species barely enters Idaho at Monida Pass (Clark County). Populations also exist in the White Mountains of east-central Arizona and the mountains of southern Utah. The species is relatively uniform throughout its range but there is often significant seasonal variation, such that plants can be compact and densely strigose in early summer but elongate and subglabrous later in the season.
Where the ranges of Potentilla plattensis and P. ovina overlap, the two are sometimes difficult to distinguish. The habitats are usually distinct, in that P. plattensis generally occurs in moist valley bottoms and P. ovina occurs in rocky uplands. Differences in vestiture are also diagnostic: hairs of P. plattensis are 0.5 mm and tightly appressed; those of P. ovina are longer and looser.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
OR
Flora NW
PNW Herbaria
SW CO Wildflowers
WildflowerSearch
iNaturalist
USDA Plants Database
