Potentilla anserina |
Potentilla elegans |
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common silverweed, Pacific cinquefoil, silver weed cinquefoil, silverweed |
elegant cinquefoil, silverweed |
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Habit | Plants densely tufted to cushion-forming; caudex branches usually short, stout, sometimes embedded in old leaves. | |||||||||||||
Stems | erect, 0.1–0.5 dm, lengths 1–2 times leaves. |
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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). |
not in ranks, ternate, 0.5–2.5(–4) cm; stipules: apex acute to obtuse; petiole 0.2–1.8(–2.5) cm, long hairs ± sparse, ± spreading, 0.2–1 mm, weak, glands sparse to abundant; leaflets 3, central obtriangular to flabellate, 0.5–0.7(–1) × 0.5–0.7 cm, petiolule 0–0.5 mm, margins flat, distal 3/4+ deeply 3–5-lobed (sinuses extending 2/3–3/4 to midvein), lobes unevenly incised 1/4–1/2 to midvein, teeth 1–3(–5) per lobe, surfaces similar, green, brownish, or reddish, hairs absent or sparse, 0.2–0.5 mm, glands sparse to common (also densely punctate-glandular). |
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Inflorescences | 1-flowered. |
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Pedicels | straight or ± curved, 0–0.5(–2) cm in flower, to 5 cm in fruit. |
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Flowers | 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, elliptic, or obovate, 2–2.2 × 0.8–1.1 mm, margins flat; hypanthium 2.5–3.5 mm diam.; sepals 2.2–2.5 mm, apex broadly acute to obtuse; petals pale yellow, 3–3.5 × 3–3.5 mm; filaments 1–1.5 mm, anthers 0.3–0.4 mm; carpels 20–25, styles ± columnar, not papillate-swollen proximally, 0.7–0.9 mm. |
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Achenes | 2 mm. |
1.2 mm. |
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2n | = 14, 28 (Russian Far East). |
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Potentilla anserina |
Potentilla elegans |
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Phenology | Flowering spring–summer. | |||||||||||||
Habitat | Rock crevices, blocky scree, mountain summits, mostly on acidic bedrock | |||||||||||||
Elevation | 100–1600 m (300–5200 ft) | |||||||||||||
Distribution |
AK; AZ; CA; CO; CT; IA; ID; IL; IN; MA; ME; MI; MN; MT; ND; NE; NH; NM; NV; NY; OH; OR; RI; SD; UT; VT; WA; WI; WY; AB; BC; MB; NB; NL; NS; NT; NU; ON; PE; QC; SK; YT; Mexico; South America (Argentina, Chile); Eurasia; Pacific Islands (New Guinea, New Zealand); s Australia
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AK; BC; NT; YT; e Asia (Russian Far East) |
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Discussion | 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.) |
For present purposes, Potentilla elegans is treated in sect. Aureae, as was done by B. C. Johnston (1985), largely on the basis of pragmatism. J. Soják (1994) places the species instead in sect. Dumosae Soják, which otherwise comprises several Himalayan species. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
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Key |
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Source | FNA vol. 9, p. 127. | FNA vol. 9, p. 194. | ||||||||||||
Parent taxa | Rosaceae > subfam. Rosoideae > tribe Potentilleae > Potentilla > sect. Pentaphylloides | Rosaceae > subfam. Rosoideae > tribe Potentilleae > Potentilla > sect. Aureae | ||||||||||||
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Subordinate taxa | ||||||||||||||
Synonyms | Argentina anserina | |||||||||||||
Name authority | Linnaeus: Sp. Pl. 1: 495. (1753) | Chamisso & Schlechtendal: Linnaea 2: 22. (1827) | ||||||||||||
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