Potentilla anserina |
Potentilla uliginosa |
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common silverweed, Pacific cinquefoil, silver weed cinquefoil, silverweed |
Cunningham Marsh cinquefoil |
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Habit | Plants rosetted to tufted; taproots not fleshy-thickened. | |||||||||||||
Stems | probably prostrate to decumbent, or ± ascending in supporting vegetation, 2.5–5.5 dm, lengths 1–2 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). |
pinnate with distal leaflets ± confluent, 15–32 × 2–4 cm; petiole 5–10(–15) cm, straight hairs absent or sparse to common, appressed, 0.5–1.5 mm, stiff, cottony hairs absent, glands absent or sparse; primary lateral leaflets 6–10(–12) per side (irregularly paired), on distal ± 1/2 of leaf axis, loosely overlapping to proximally separate, largest ones cuneate to flabellate, 1.2–2.2 × 1–3 cm, ± whole margin unevenly incised 3/4 to nearly to midvein, ultimate segments (3–)5–10(–15), linear to narrowly oblanceolate, 5–17 × 1–2.5 mm, apical tufts less than 0.5 mm, surfaces green, not glaucous, straight hairs sparse (often glabrate adaxially), appressed, 0.5–1(–1.5) mm, stiff, cottony hairs absent, glands absent or sparse. |
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Cauline leaves | 2. |
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Inflorescences | 6–10-flowered, very openly cymose. |
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Pedicels | 1–6 cm, ± recurved 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 narrowly elliptic to oblong-ovate, 4–6 × 1–2.5 mm; hypanthium 5–6 mm diam.; sepals 4–7 mm, apex acute; petals 6–10 × 5–8 mm; filaments (1.5–)2–3 mm, anthers 0.7–1.2 mm; carpels ca. 10, styles 2.5–3.5 mm. |
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Achenes | 2 mm. |
2–2.6 mm, smooth, ± carunculate. |
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Potentilla anserina |
Potentilla uliginosa |
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Phenology | Flowering spring–summer. | |||||||||||||
Habitat | Permanent oligotrophic wetlands | |||||||||||||
Elevation | 30–40 m (100–100 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 uliginosa is known only from a handful of historical collections from Cunningham Marsh, one of three wetlands in southern Sonoma County that harbor a suite of disjunct and regionally rare species (B. C. Johnston and B. Ertter 2010). Although previously included in P. hickmanii, P. uliginosa differs in having woodier caudices, longer stems and leaves, and more deeply incised leaflets occupying less of the leaf axis. Potentilla uliginosa is presumed extinct; however, a morphologically comparable collection of the P. millefolia complex from Josephine County, Oregon (Deer Creek, near Selma, 14 June 1929, Applegate 5735, UC), opens the possibility of additional undiscovered populations in the mountains of northwestern California. (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. 175. | ||||||||||||
Parent taxa | Rosaceae > subfam. Rosoideae > tribe Potentilleae > Potentilla > sect. Pentaphylloides | Rosaceae > subfam. Rosoideae > tribe Potentilleae > Potentilla > sect. Multijugae | ||||||||||||
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Subordinate taxa | ||||||||||||||
Synonyms | Argentina anserina | |||||||||||||
Name authority | Linnaeus: Sp. Pl. 1: 495. (1753) | B. C. Johnston & Ertter: J. Bot. Res. Inst. Texas 4: 14, fig. 1. (2010) | ||||||||||||
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