Potentilla anserina |
Potentilla thuringiaca |
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common silverweed, Pacific cinquefoil, silver weed cinquefoil, silverweed |
European cinquefoil, German cinquefoil, potentille de thuringe |
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Glands | sparse, uncolored, minute. |
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Stems | 1.5–5(–7) dm. |
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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). |
4–25(–35) cm; petiole 2–20(–25) cm, hairs sparse to common, ± spreading, 1–2.5 mm, weak, glands absent or sparse; leaflets 5–7(–9), central one narrowly to broadly oblanceolate, 1–6(–9) × 0.5–2 cm, distal 2/3–3/4+ of margin incised 1/4–1/3(–1/2) to midvein, teeth (4–)6–10(–13) per side, surfaces ± similar, abaxial green to pale green, hairs sparse to common on primary veins, ascending to spreading, 0.5–1.5 mm, weak, adaxial green, hairs more appressed and shorter. |
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Cauline leaves | 1–3; stipules fused with less than 1/3 of petiole, free portion longer than fused portion. |
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Inflorescences | 5–20-flowered. |
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Pedicels | 1–3 cm (proximalmost to 5 cm). |
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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 to lanceolate, 3–8 × 1–1.5(–2) mm; hypanthium 3–5 mm diam.; sepals 3–5 mm, apex ± acute; petals (5–)8–10 × 4–10 mm; filaments 0.3–1.5 mm, anthers 0.7–0.9 mm; carpels 35–50, styles 1.1–1.3 mm. |
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Achenes | 2 mm. |
1–1.2 mm, faintly rugose. |
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2n | = 42, 56 (Eurasia). |
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Potentilla anserina |
Potentilla thuringiaca |
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Phenology | Flowering late spring–summer. | |||||||||||||
Habitat | Edges of and openings in hardwood and conifer woodlands | |||||||||||||
Elevation | 0–100 m (0–300 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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RI; QC; Eurasia [Introduced in North America] |
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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.) |
Potentilla thuringiaca might be mistaken for the more widely established P. intermedia of sect. Terminales. In addition to having flowering stems lateral to persistent basal leaves, P. thuringiaca has much larger petals (mostly 8–10 mm versus 4–5 mm), 5–9 leaflets, and tubercles at the bases of the long, spreading hairs. To the Quebec records (and subsequent collections) reported by R. Cayouette (1966) is added Block Island, Rhode Island (Fernald et al. 9650, GH). (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. 146. | ||||||||||||
Parent taxa | Rosaceae > subfam. Rosoideae > tribe Potentilleae > Potentilla > sect. Pentaphylloides | Rosaceae > subfam. Rosoideae > tribe Potentilleae > Potentilla > sect. Chrysanthae | ||||||||||||
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Subordinate taxa | ||||||||||||||
Synonyms | Argentina anserina | P. chrysantha subsp. thuringiaca, P. goldbachii, P. nestleriana | ||||||||||||
Name authority | Linnaeus: Sp. Pl. 1: 495. (1753) | Bernhardi ex Link: Enum. Hort. Berol. Alt. 2: 64. (1822) | ||||||||||||
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