Potentilla plattensis
Potentilla argentea
Platte cinquefoil, Platte River cinquefoil
hoary cinquefoil, potentille argentée, silver cinquefoil, silver-leaf cinquefoil, silvery 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.
mostly decumbent to ascending, 1–6 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.
palmate.
1–3.
2–9, proximal ones 2–7(–10) cm;
proximal petioles 1–4(–7) cm, long hairs absent or sparse, ± ascending, 1–2 mm, soft, short and crisped hairs absent or obscured, cottony hairs dense, glands absent or obscured;
leaflets 5(–7), central one ± oblanceolate, (0.5–)1–3 × 0.3–1(–1.3) cm, margins revolute, distal 1/2–2/3 evenly or unevenly incised 1/2–3/4+ to midvein, teeth 2–3 per side (more if lobed or secondarily toothed), surfaces strongly dissimilar, abaxial white, long hairs ± sparse (mostly on veins), 1–2 mm, weak, short and crisped hairs absent or obscured, cottony hairs dense, glands absent or obscured, adaxial long hairs absent or sparse to common, short or crisped hairs absent or sparse, cottony hairs absent, glands absent or sparse.
(1–)3–15(–20)-flowered, loosely cymose, sometimes racemiform.
10–80-flowered.
1–4(–5) cm, ± recurved in fruit.
0.3–1.5(–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 oblong to narrowly ovate, 1.5–3 × 0.7–1.2 mm, lengths 2/3–1 times sepals;
sepals 2–4.5 mm, apex ± acute;
petals (2–)2.5–4 × 1.5–3 mm;
filaments 0.8–1.5 mm, anthers 0.3–0.6(–0.8) mm;
carpels 30–60, styles 0.6–0.9 mm, often strongly papillate-swollen proximally.
(1.3–)1.5–1.9 mm, smooth, often ± carunculate.
0.8–1.1 mm, smooth to lightly rugose.
= 70.
= 14, 28, 35, 42, 56, 62 (Eurasia).
Potentilla plattensis
Potentilla argentea
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.)
The bright, silvery vestiture of the leaves quickly distinguishes Potentilla argentea from P. inclinata and P. intermedia. Although treated here as introduced, some (P. A. Rydberg 1898; P. A. Werner and J. D. Soule 1976) considered P. argentea to be probably native in eastern North America.
The Potentilla argentea species group is an amphi- or apomictic polyploid complex that has been the subject of numerous cytological, sexual, and molecular studies (for example, A. Müntzing and G. Müntzing 1945; A. Müntzing 1958; J. Paule et al. 2011). Taxonomic treatments have ranged from a highly polymorphic single species to an abundance of species, varieties, and forms (T. Wolf 1908). This treatment is at the conservative end of the spectrum. Some New England references (R. C. Bean et al. 1967; F. C. Seymour 1969) distinguish plants with densely white-hairy adaxial leaflet surfaces as var. pseudocalabra Th. Wolf, a name based on plants from southeastern Europe. Molecular analysis by Paule et al. supports the conclusion by Wolf that the variety consists of intermediates between P. argentea and P. calabra Tenore. The optimum taxonomic disposition of var. pseudocalabra, and whether any North American plants are properly included, remains to be determined.
Potentilla argentea has been reported as an active agent in treating cirrhosis of the liver (N. T. Starostenko and V. N. Starostenko 1971).
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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