Potentilla plattensis
Potentilla angelliae
Platte cinquefoil, Platte River cinquefoil
Angell's or Boulder Mountain cinquefoil, Boulder Mountain 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.
(0.4–)0.6–1.1 dm, lengths 2–3 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.
subpinnate, 1 pair of leaflets separate from terminal leaflets, distal leaflets distinct, 1.5–5 cm;
petiole 0.5–3(–4) cm, straight hairs abundant, loosely appressed to ascending, 1–2 mm, stiff, cottony hairs absent, glands sparse to abundant;
leaflets 5, on distal (1/10–)1/5–1/4 of leaf axis, separate, proximal pair separated from others by 1–3 mm of leaf axis, central leaflets narrowly cuneate to oblanceolate, 0.5–1.5 × 0.3–0.6 cm, petiolules 1 mm, distal 1/4(–1/3) or less of margins incised 1/2 or less to midvein, teeth (0–)1(–2) per side, ± separate, 1 mm, surfaces ± dissimilar, abaxial grayish to white, straight hairs ± abundant, appressed, 1–1.5 mm, ± stiff, cottony hairs abundant to sparse, glands ± sparse or obscured, adaxial greenish, straight hairs abundant, ± appressed, 1–1.5(–2) mm, stiff, cottony hairs absent, glands sparse to abundant.
1–3.
(1–)3–15(–20)-flowered, loosely cymose, sometimes racemiform.
solitary flowers or 2–3-flowered.
1–4(–5) cm, ± recurved in fruit.
(1–)1.5–3 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 to ovate, 2–4 × 0.8–1.5 mm;
hypanthium 3–5 mm diam.;
sepals 3–5(–6) mm, apex ± acute;
petals (4–)5–6.5 × 4–5.5 mm;
filaments 1.5–2.5 mm, anthers 0.7–1 mm;
carpels 10–30, styles 2–2.5 mm.
(1.3–)1.5–1.9 mm, smooth, often ± carunculate.
1.5–2 mm, smooth to faintly rugose.
= 70.
Potentilla plattensis
Potentilla angelliae
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 angelliae is known only from Boulder Mountain on the Aquarius Plateau in Garfield and Wayne counties. Comparable plants, whose status has yet to be resolved, have been collected in Montezuma County, Colorado. S. L. Welsh et al. (1993) suggested that P. angelliae might best be treated as a variety of P. concinna; the combination of subpalmate leaves, tridentate leaflets, and relatively few-flowered inflorescences extending beyond the leaves makes P. angelliae a well-defined species with no evidence of intergradation.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
OR
Flora NW
PNW Herbaria
SW CO Wildflowers
WildflowerSearch
iNaturalist
USDA Plants Database
