Potentilla plattensis
Potentilla albiflora
Platte cinquefoil, Platte River cinquefoil
Pinaleño cinquefoil, whiteflower 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.
0.2–1.5 dm.
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.
ternate, 1.5–10 cm;
petiole 1–7 cm, long hairs ± abundant, spreading to ascending, 0.5–1(–1.5) mm, weak to stiff, glands sparse to abundant;
leaflets 3, central obovate, 0.5–2.5(–3.5) × 0.4–1.3(–2) cm, not to scarcely petiolulate, distal 1/2–2/3 of margins evenly incised ± 1/3 to midvein, teeth 3–5(–6) per side, surfaces green, long hairs ± abundant, 0.5–1 mm, glands sparse to abundant.
1–3.
(1–)3–15(–20)-flowered, loosely cymose, sometimes racemiform.
1–5(–10)-flowered.
1–4(–5) cm, ± recurved in fruit.
0.5–2 cm.
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 lanceolate-elliptic, (1.5–)2–3(–5) × 0.5–1.5 mm;
hypanthium 3.5–6 mm diam.;
sepals 3–6(–8) mm, apex acute;
petals ± paler abaxially, bright yellow adaxially, narrowly obcordate, (3–)4–7(–8) × 3–5 mm;
filaments 2–4 mm, anthers 0.5–1 mm;
carpels 10–25, styles 2–3 mm.
(1.3–)1.5–1.9 mm, smooth, often ± carunculate.
1.5 mm, smooth.
hairs not well differentiated from long hairs, absent or sparse throughout.
= 70.
Potentilla plattensis
Potentilla albiflora
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 albiflora grows on the Pinaleño (Graham) Mountains in Graham County, with a few outlying collections known from the Mogollon Rim in Greenlee County and the Santa Catalina Mountains of Pima County.
Contrary to the specific epithet, petals of living plants are yellow, not white; like those of many Potentilla species, they tend to fade in pressed material.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
OR
Flora NW
PNW Herbaria
SW CO Wildflowers
WildflowerSearch
iNaturalist
USDA Plants Database
