Potentilla anserina |
Potentilla cristae |
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common silverweed, Pacific cinquefoil, silver weed cinquefoil, silverweed |
crested cinquefoil, crested potentilla |
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Habit | Plants tufted to densely matted; caudex branches usually short, stout, sometimes embedded in old leaf bases. | |||||||||||||
Stems | ascending to erect, 0.3–2 dm, lengths 2–3 times basal 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, 1–5(–9) cm; stipules: apex acute to obtuse; petiole 1–4 cm, long hairs absent or sparse to common, spreading to ascending, 0.5–2 mm, ± weak, glands sparse to abundant; leaflets 3, central flabellate, 0.4–2 × 0.5–1.5 cm, petiolule 1–3 mm, margins flat, distal 3/4+ deeply 3–5-lobed (sinuses extending 1/2 to nearly to midvein), lobes unevenly incised 1/4–1/2 to midvein, teeth 2–5 per lobe, surfaces similar, dark green, hairs ± sparse, 0.5–1.5 mm, glands sparse to abundant. |
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Inflorescences | 1–7-flowered. |
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Pedicels | straight, 0.2–1.2(–2) cm, not much longer in fruit than in flower. |
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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 broadly ovate, 2–4 × 2 mm, margins flat; hypanthium 3.5–6 mm diam.; sepals 3–5 mm, apex broadly acute to obtuse; petals yellow, 3–5.5 × 4–5 mm; filaments 0.7–1.7 mm, anthers 0.5–0.6 mm; carpels 25–40, styles tapered-filiform, ± papillate-swollen in proximal 1/5–/1/3, 1.3–2 mm. |
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Achenes | 2 mm. |
1–1.5 mm, dorsally crested. |
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2n | = 42. |
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Potentilla anserina |
Potentilla cristae |
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Phenology | Flowering summer. | |||||||||||||
Habitat | Rocky, open, serpentine slopes, in conifer woodlands | |||||||||||||
Elevation | 1800–2800 m (5900–9200 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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CA |
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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.) |
Of conservation concern. Potentilla cristae is known only from Cory Peak, Mount Eddy, and the Marble Mountains in northwestern California. In addition to the characteristics in the key, the species is distinctive in having a low dorsal crest on the achenes, hence the specific epithet. (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. 191. | ||||||||||||
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) | Ferlatte & Strother: Madroño 37: 190, fig. 1. (1990) | ||||||||||||
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