Potentilla anserina |
Potentilla anserina subsp. groenlandica |
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common silverweed, Pacific cinquefoil, silver weed cinquefoil, silverweed |
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Stems | glabrous. |
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Leaves | horizontal or ascending, rarely erect, (1–)2–10 cm, rarely longer; leaflets 2–4(–5) per side, separate, teeth 2–6(–10) per side, teeth apex rounded to subacute, surfaces: abaxial with long hairs absent or sparse, on veins, cottony-crisped hairs absent, sometimes sparse to dense, adaxial glabrous. |
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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). |
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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). |
0.8–1.5 cm diam.; epicalyx bractlets narrowly to broadly ovate-triangular, shorter than sepals, entire; hypanthium patelliform (wider than deep) in fruit; petals not overlapping, elliptic; carpels 25–60. |
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Achenes | 2 mm. |
without dorsal groove. |
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2n | = 28, 35, 42. |
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Potentilla anserina |
Potentilla anserina subsp. groenlandica |
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Phenology | Flowering summer. | |||||||||||||
Habitat | Salt and brackish marshes, clayey and sandy seashores, driftwalls | |||||||||||||
Elevation | 0 m (0 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; LB; MB; NT; NU; ON; QC; YT; Greenland; Eurasia |
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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.) |
The northern arctic plants have glabrous leaves and are compatible with Potentilla egedei. Some of the southern arctic and northern boreal plants in the Atlantic regions have leaves with white-hairy abaxial surfaces, more leaflets, often more pointed teeth, and slightly larger flowers. These are compatible with subsp. groenlandica as originally described. The variation between these extremes is continuous. Both names are based on plants from Greenland, far north of the native range of subsp. anserina, and are probably the same entity. Following the argument by J. Soják (1969) that trinomials by Trattinnick are subspecies, the epithet groenlandica has priority over egedei at this rank. (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. 130. | ||||||||||||
Parent taxa | Rosaceae > subfam. Rosoideae > tribe Potentilleae > Potentilla > sect. Pentaphylloides | Rosaceae > subfam. Rosoideae > tribe Potentilleae > Potentilla > sect. Pentaphylloides > Potentilla anserina | ||||||||||||
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Subordinate taxa | ||||||||||||||
Synonyms | Argentina anserina | Argentina anserina subsp. egedei, A. anserina subsp. groenlandica, A. egedei, P. anserina subsp. egedei, P. egedei, P. egedei var. groenlandica | ||||||||||||
Name authority | Linnaeus: Sp. Pl. 1: 495. (1753) | Trattinnick: Rosac. Monogr. 4: 13. (1824) | ||||||||||||
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