Potentilla plattensis
Potentilla modesta
Platte cinquefoil, Platte River cinquefoil
modest cinquefoil
usually not sheathed with marcescent whole leaves.
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.
ascending to nearly erect, (0.3–)0.5–1.5(–2.5) 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.
usually palmate, rarely also ternate on same plant or subpalmate, 2–6(–8) cm;
petiole 0.5–3.5(–5) cm, long hairs common to abundant, ± ascending to almost spreading, 1–2 mm, weak to ± stiff, scarcely to ± verrucose, short and/or crisped hairs common to abundant, cottony hairs absent, glands sparse to common;
leaflets (3–)5, proximalmost separated by 0–1 mm, central obovate to oblanceolate-elliptic, 0.5–2(–2.5) × 0.5–1(–1.5) cm, petiolules 1 mm, distal 3/4 to nearly whole margin incised 1/2–3/4 to midvein, teeth 2–5 per side, (1–)2–5 mm, apical tufts 0.5–1 mm, abaxial surfaces white, long hairs common to abundant, cottony-crisped hairs dense, short hairs and glands absent or obscured, adaxial grayish green, long hairs common to abundant, 0.5–1.5 mm, ± stiff, rarely soft, short and/or crisped hairs sparse to common, cottony hairs absent, glands sparse to common.
1–3.
1–2.
(1–)3–15(–20)-flowered, loosely cymose, sometimes racemiform.
(1–)3–10-flowered, congested or ± elongating in fruit, branch angle 20–35°.
1–4(–5) cm, ± recurved in fruit.
0.2–0.5 cm, proximal to 1.2 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 narrowly elliptic, 1.5–3 × 0.5–1 mm;
hypanthium 3–4 mm diam.;
sepals 2.5–4 mm, apex ± acute, glands abundant, usually not obscured;
petals yellow, ± overlapping, 3.5–5 × 3–4 mm, slightly longer than sepals;
filaments 1 mm, anthers 0.3–0.7 mm;
carpels 20–40, styles 1 mm.
(1.3–)1.5–1.9 mm, smooth, often ± carunculate.
1 mm.
= 70.
Potentilla plattensis
Potentilla modesta
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.)
Potentilla modesta is the dominant component of what has previously been called P. rubricaulis in the Intermountain Region (for example, N. H. Holmgren 1997b, including illustration). This and other species of alpine Potentilla often grow in mixed populations, which contributes to confusion and mistaken identifications. In general, P. modesta has a more compact inflorescence and more consistently palmate basal leaves than sympatric members of the section. Intergrades with P. jepsonii (sect. Pensylvanicae) can also be problematic, though leaves of the latter are generally subpinnate and abaxially grayish rather than white.
The epithet modesta is misapplied in the combination Potentilla concinna var. modesta, which S. L. Welsh et al. (1993) used for plants mostly placed here in P. concinna var. divisa (sect. Concinnae).
(Discussion copyrighted by Flora of North America; reprinted with permission.)
OR
Flora NW
PNW Herbaria
SW CO Wildflowers
WildflowerSearch
iNaturalist
USDA Plants Database
