Potentilla anserina
Potentilla ambigens
common silverweed, Pacific cinquefoil, silver weed cinquefoil, silverweed
silkyleaf cinquefoil, silkyleaf or giant or southern Rocky Mountain cinquefoil
(2–)3–7(–8) dm, lengths (1–)1.5–2.5 times basal leaves.
petiole (0.5–)1–15(–25) cm, long hairs absent or sparse to dense, 1.5–3.5 mm;
larger leaflets (0.4–)0.5–5(–7) × (0.2–)0.3–2(–3) cm, surfaces: abaxial with long hairs absent or sparse to abundant, not restricted to veins, 0.5–2(–2.5) mm, cottony-crisped hairs usually dense or usually absent (in subsp. groenlandica), adaxial with long hairs absent or sparse to abundant, cottony-crisped hairs usually absent, sometimes sparse to common (especially subsp. yukonensis).
pinnate, 15–45(–50) cm;
petiole (5–)8–20 cm, long hairs abundant to dense, ascending to appressed, (1–)2–3 mm, ± stiff, rarely weak, short or crisped hairs absent or sparse, cottony hairs absent, glands sparse, often obscured;
leaflets not conduplicate, lateral ones evenly paired, (3–)4–7 per side on distal ± 1/2 of leaf axis, most pairs ± decurrent, rachis winged, distal sometimes confluent with terminal leaflet, larger leaflets narrowly obovate, (2–)3–7 × 1–2.5 cm, distal 3/4+ of margin incised 1/3 to midvein, teeth 6–18 per side, 1–4 mm, surfaces ± similar, abaxial grayish, long hairs sparse to common (mostly on veins), 0.5–2 mm, ± stiff, rarely weak, short-crisped hairs absent or sparse to common, cottony hairs absent, glands sparse to common, adaxial green to grayish, long and short hairs not differentiated, sparse to common, crisped and cottony hairs absent, glands absent or sparse.
(0–)1–3.
(10–)20–60-flowered.
(0.5–)1–3(–6) cm.
epicalyx bractlets narrowly to broadly ovate-triangular or linear to elliptic, (2–)2.5–7(–8) × (0.3–)0.5–3(–3.5) mm, often 2-fid or dentate;
sepals (3–)3.5–7(–9) mm, apex subacute to acuminate;
petals (4–)5–15(–20) × (2.5–)3–10(–12) mm;
filaments (1–)2.5–3.5(–4.5) mm, anthers 0.7–1.3 mm;
carpels (10–)20–200(–250).
epicalyx bractlets lanceolate to narrowly ovate or elliptic, 3–6 × 1–1.5 mm, 2/3 as long as to nearly equal to sepals, abaxial vestiture ± similar to sepals, not glabrescent, straight hairs sparse to common, crisped or cottony hairs usually absent;
hypanthium 3–6 mm diam.;
sepals 4–7 mm, apex acute to acuminate;
petals (6–)7–10 × 5–9 mm;
filaments (1–)1.5–4 mm, anthers 0.7–0.9(–1) mm;
carpels 20–30, styles (1–)1.8–3 mm.
2 mm.
1.4–1.6 mm, smooth.
= 82.
Potentilla anserina
Potentilla ambigens
Subspecies 4 or 5 (4 in the flora).
Potentilla anserina is polymorphic in most features, especially in hairiness, but also in size and in degree of dissection of leaflets, epicalyx bractlets, and sepals. While most of the variation described by A. G. Blytt (1906) is taxonomically insignificant, A. Rousi (1965) found support for three northern races: subspp. anserina, egedei, and pacifica. He also suggested that P. yukonensis Hultén might qualify as a separate subspecies. This treatment follows J. Soják (1994) in accepting four northern subspecies of P. anserina, all present in North America.
A. Rousi (1965) demonstrated partial interfertility between the races of Potentilla anserina, which form intermediates in all zones of contact. The distinctness of the four races, in spite of intermediates, is upheld by being partly allopatric and occupying different habitats where they are sympatric. As partly interfertile parapatric entities, they are best treated as subspecies.
The vast majority of chromosome counts are tetraploid. Tetraploid plants (2n = 28) are fully fertile; hexaploids (2n = 42) are largely pollen and seed sterile; pentaploids (2n = 35) are probably occasional hybrids (S. Erlandsson 1942, 1942b; A. Rousi 1965). A. Kurtto et al. (in J. Jalas et al. 1972+, vol. 13) considered numbers above tetraploid level as cases of occasional autopolyploidy.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
Of conservation concern.
Potentilla ambigens is one of the more distinctive species in sect. Leucophyllae, comprising exceptionally large plants with large, coarsely hairy leaves. Although sometimes confused with P. hippiana, P. ambigens lacks the crisped-cottony vestiture of that species and is usually morphologically distinctive even where both species occur together (D. G. Anderson, www.fs.fed.us/r2/projects/scp/assessments/potentillaambigens.pdf).
Potentilla ambigens occurs in Wyoming (at least historically), along the eastern slope of the Rocky Mountains to northern Colorado, and in scattered locations in the high mountains of New Mexico as far south as the Sacramento Mountains, Otero County. The species is of conservation concern in Colorado and has not been documented in Wyoming since 1900 (D. G. Anderson, www.fs.fed.us/r2/projects/scp/assessments/potentillaambigens.pdf).
(Discussion copyrighted by Flora of North America; reprinted with permission.)
1. Epicalyx bractlets equal to or longer than sepals, often 2-fid or dentate; leaflet surfaces: abaxial with cottony-crisped hairs dense, long hairs common to abundant, on and between veins, adaxial glabrous or sparsely to densely hairy; achenes with dorsal groove; inland and seashore plants | → 2 |
1. Epicalyx bractlets shorter than sepals, usually entire, rarely 2-fid or dentate; leaflet surfaces: abaxial with cottony-crisped hairs absent or sparse to dense, long hairs absent or sparse, on veins, adaxial usually glabrous, rarely sparsely to densely hairy; achenes without dorsal groove; seashore or near-coastal plants | → 3 |
2. Hypanthium patelliform (wider than deep) in fruit; epicalyx bractlets narrowly to broadly ovate-triangular, equal to sepals; most of North America. | subsp. anserina |
2. Hypanthium turbinate (± as deep as wide) in fruit; epicalyx bractlets usually linear to elliptic, longer than sepals, rarely subequal; interior w Canada and Alaska. | subsp. yukonensis |
3. Carpels (20–)50–200(–250); leaves (3–)10–50(–75) cm; leaflets (4–)5–10(–15) per side, abaxial surfaces densely hairy, teeth (4–)6–12(–16) per side, teeth apices acute to acuminate, rarely subacute; flowers 1–2.5(–3.5) cm diam. | subsp. pacifica |
3. Carpels 25–60; leaves (1–)2–10 cm, rarely longer; leaflets 2–4(–5) per side, abaxial surfaces glabrous, sometimes sparsely to densely hairy, teeth 2–6(–10) per side, teeth apices rounded to subacute; flowers 0.8–1.5 cm diam. | subsp. groenlandica |
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OR, 
WA - Local Web sites: CalFlora, CalPhotos,
Flora NW, 
IL Wildflowers, 
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MN Wildflowers, 
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