Potentilla anserina |
Potentilla intermedia |
|||||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
common silverweed, Pacific cinquefoil, silver weed cinquefoil, silverweed |
downy cinquefoil, potentille intermédiaire |
|||||||||||||
Stems | ascending to erect, 2–5 dm. |
|||||||||||||
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). |
palmate or ternate. |
||||||||||||
Cauline leaves | 3–8, proximal ones (3–)5–14 cm; proximal petioles (1–)2–10 cm, long hairs sparse to common, spreading to loosely appressed, 1–2 mm, weak, short or crisped hairs sparse to common, cottony hairs absent, glands absent or sparse; leaflets usually 5, central one oblanceolate to obovate, 2–4.5 × 1–2.5 cm, margins ± flat, distal 3/4+ usually unevenly, sometimes evenly, incised 1/3–2/3 to midvein (often with 1–2 incisions nearly to midvein), teeth 5–10 per side, surfaces similar or ± dissimilar, abaxial green to grayish green, long hairs sparse to common (especially on veins), 0.5–1.5 mm, soft to weak, short or crisped hairs ± sparse, cottony hairs absent, glands absent or sparse, adaxial long hairs absent or sparse, 1 mm, short hairs absent or sparse, crisped and cottony hairs absent, glands absent or sparse. |
|||||||||||||
Inflorescences | 20–100+-flowered. |
|||||||||||||
Pedicels | 0.5–1.5(–2.5) cm. |
|||||||||||||
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 lanceolate to ovate or elliptic, 2–5 × 0.8–1.5 mm, lengths usually 2/3, sometimes 1, times sepals; sepals 3.5–6.5 mm, apex ± acute; petals 3–5 × 2–3 mm; filaments 0.8–2 mm, anthers 0.3–0.5 mm; carpels 40–70, styles 1–1.2 mm, scarcely papillate-swollen proximally. |
||||||||||||
Achenes | 2 mm. |
1 mm, rugose. |
||||||||||||
2n | = 28, 56 (Eurasia). |
|||||||||||||
Potentilla anserina |
Potentilla intermedia |
|||||||||||||
Phenology | Flowering late spring–summer. | |||||||||||||
Habitat | Dry waste places along roadsides, ditches, other open sites, in grasslands, oak and conifer woodlands | |||||||||||||
Elevation | 0–300 m (0–1000 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
|
CT; IA; IN; MA; ME; MI; NH; NJ; NY; OH; PA; RI; VT; WI; NB; NF; NS; ON; PE; QC; SPM; Eurasia [Introduced in North America]
|
||||||||||||
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 intermedia is more common than P. inclinata at least in eastern Canada and New England. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
||||||||||||
Key |
|
|||||||||||||
Source | FNA vol. 9, p. 127. | FNA vol. 9, p. 145. | ||||||||||||
Parent taxa | Rosaceae > subfam. Rosoideae > tribe Potentilleae > Potentilla > sect. Pentaphylloides | Rosaceae > subfam. Rosoideae > tribe Potentilleae > Potentilla > sect. Terminales | ||||||||||||
Sibling taxa | ||||||||||||||
Subordinate taxa | ||||||||||||||
Synonyms | Argentina anserina | P. heidenreichii | ||||||||||||
Name authority | Linnaeus: Sp. Pl. 1: 495. (1753) | Linnaeus: Syst. Nat. ed. 12, 2: 351. (1767): Mant. Pl. 1: 76. (1767) | ||||||||||||
Web links |
|