Potentilla anserina
Potentilla rubricaulis
common silverweed, Pacific cinquefoil, silver weed cinquefoil, silverweed
red-stem cinquefoil, Rocky Mountain cinquefoil
not sheathed with marcescent whole leaves.
ascending to nearly erect, 1.5–4 dm.
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).
often both ternate and palmate on same plant, rarely subpalmate, 4–10 cm;
petiole 2.5–7 cm, long hairs sparse to common, loosely appressed to ascending-spreading, 1–2 mm, ± weak to stiff, verrucose, short and/or ± crisped hairs common to abundant, cottony hairs absent, glands usually sparse;
leaflets 3–5, proximalmost separated by 0(–1) mm, central oblong to obovate, 1.5–4 × 1–2.5 cm, petiolules 0–5 mm, distal 2/3–3/4 of margin incised 1/2–3/4, rarely +, to midvein, teeth (4–)5–8 per side, 4–5 mm, apical tufts 1 mm, abaxial surfaces gray to grayish white, long hairs abundant, cottony-crisped hairs usually dense, short hairs and glands absent or obscured, adaxial green to grayish green, long hairs sparse to common, 0.5–1.5 mm, stiff, short hairs absent or sparse, rarely common, crisped and cottony hairs absent, glands absent or sparse, rarely common.
2–3.
4–20-flowered, open, branch angle (10–)20–45°.
0.5–3 cm, proximal to 5 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 linear to narrowly lanceolate, 3–4 × 0.8–1.2 mm;
hypanthium 4–6 mm diam.;
sepals 4–5 mm, apex subacute to acute, glands usually ± sparse, not obscured;
petals pale yellow, not overlapping, 5–7 × (4–)5–6.5 mm, distinctly longer than sepals;
filaments 0.5–1.5 mm, anthers 0.4 mm;
carpels 30–60, styles 0.9–1.1 mm.
2 mm.
1.2 mm.
= 56.
Potentilla anserina
Potentilla rubricaulis
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.)
As addressed by B. Ertter et al. (2013), the name Potentilla rubricaulis is here restricted to relatively large plants with open inflorescences occurring mainly in glaciated parts of subarctic northwestern Canada and Alaska. Plants from the Chugach Mountains of southern Alaska tend to be more conspicuously glandular than elsewhere.
The distinction between Potentilla rubricaulis and large forms of P. arenosa with supernumerary leaflets is problematic. Although both species have somewhat similar petiole vestiture (long, straight, verrucose hairs and a layer of short, stiff, or curly hairs), the latter species tends to have more stiffly spreading petiole hairs and prominently petiolulate central leaflets.
The octoploid chromosome count (P. M. Dansereau and E. Steiner 1956) from Great Bear Lake area, Northwest Territories, probably belongs to Potentilla rubricaulis in the narrow sense, since that is its type locality.
(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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