Potentilla anserina |
Potentilla townsendii |
|||||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
common silverweed, Pacific cinquefoil, silver weed cinquefoil, silverweed |
Townsend's cinquefoil |
|||||||||||||
Glands | absent or inconspicuous, uncolored. |
|||||||||||||
Stems | ascending to nearly erect, (1–)2–5(–7.5) 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). |
usually not in ranks, palmate, rarely subpalmate, (2–)5–20(–30) cm; petiole (1–)2–15(–25) cm, long hairs usually absent or sparse and appressed, sometimes common and spreading, 1–1.5 mm, stiff, short, crisped, and cottony hairs absent, glands absent; leaflets 5–7(–8), usually on tip, rarely on less than distal 1/10, of leaf axis, separate, largest ones narrowly oblanceolate-elliptic, (1.5–)2–5(–6) × 0.5–1.2(–1.5) cm, margins flat, distal (1/4–)1/2–3/4 evenly incised 1/4–1/3 to midvein, undivided medial blade 4–11 mm wide, teeth (2–)4–8(–9) per side, mostly broadly lanceolate, 1–2 mm, surfaces similar, green, not glaucous, long hairs usually absent or limited to veins and margins, short, crisped, and cottony hairs absent, glands absent. |
||||||||||||
Cauline leaves | 1–3. |
|||||||||||||
Inflorescences | (5–)10–20(–25)-flowered. |
|||||||||||||
Pedicels | 0.7–3(–3.5) 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 elliptic, (2–)2.5–5(–6) × 0.5–1(–1.4) mm, hairs sparse, ± appressed, glands absent; hypanthium 3.5–5 mm diam.; sepals 4–8(–9) mm, apex acute to long acuminate; petals 5–10 × 5–10(–12) mm; filaments 1–3 mm, anthers (0.5–)0.6–1 mm; carpels 15–30, styles filiform above papillate-swollen base, (1–)1.5–2 mm. |
||||||||||||
Achenes | 2 mm. |
1.1–1.6 mm. |
||||||||||||
Potentilla anserina |
Potentilla townsendii |
|||||||||||||
Phenology | Flowering summer. | |||||||||||||
Habitat | Edges of meadows, dry gravelly flats and slopes, in montane to subalpine conifer woodlands, mixed grassland communities | |||||||||||||
Elevation | (2300–)2700–3700 m ((7500–)8900–12100 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
|
AZ; NM; Mexico (Chihuahua) |
||||||||||||
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.) |
Although previously applied only to collections from Chihuahua, Mexico, Potentilla townsendii is here used to accommodate most plants from Arizona and New Mexico previously placed in P. glaucophylla (as P. diversifolia Lehmann). Plants have narrow, shallowly toothed leaflets; stems, petioles, and leaflet veins that are often reddish; and larger anthers than P. glaucophylla. As now circumscribed, P. townsendii is known in the United States primarily from the White Mountains of east-central Arizona and the high mountains of northern New Mexico. Whether these plants are truly conspecific with those from Chihuahua, Mexico, remains to be confirmed. The species might also occur in Colorado and Utah, but the best disposition of these problematic populations is uncertain. Somewhat hairy plants with subpalmate leaves are interpreted as introgression from P. hippiana or other species. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
||||||||||||
Key |
|
|||||||||||||
Source | FNA vol. 9, p. 127. | FNA vol. 9, p. 153. | ||||||||||||
Parent taxa | Rosaceae > subfam. Rosoideae > tribe Potentilleae > Potentilla > sect. Pentaphylloides | Rosaceae > subfam. Rosoideae > tribe Potentilleae > Potentilla > sect. Graciles | ||||||||||||
Sibling taxa | ||||||||||||||
Subordinate taxa | ||||||||||||||
Synonyms | Argentina anserina | |||||||||||||
Name authority | Linnaeus: Sp. Pl. 1: 495. (1753) | Rydberg: Bull. Torrey Bot. Club 28: 174. (1901) | ||||||||||||
Web links |
|