Potentilla anserina
Potentilla jepsonii
common silverweed, Pacific cinquefoil, silver weed cinquefoil, silverweed
Jepson's cinquefoil, Jepson's potentilla
decumbent to nearly erect, (0.2–)0.5–2.6 dm.
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).
subpinnate to subpalmate, 1.5–10(–17) cm;
petiole 0.5–4(–8) cm, long hairs ± abundant, spreading to loosely appressed, 0.5–2 mm, weak to stiff, short hairs absent or sparse, cottony or crisped hairs absent, glands sparse to abundant;
leaflets (1–)2–3 per side, on distal 1/6–1/3(–1/2) of leaf axis, separate to slightly overlapping, terminal ones oblanceolate-elliptic to narrowly obovate, (0.5–)1–2.5(–3.5) × 0.4–1(–1.3) cm, margins strongly revolute, incised 3/4+ to midvein, undivided medial blade 1.5–3(–5) mm wide, teeth (2–)3–5(–6) per side, ± linear-elliptic to rarely ovate or oblanceolate, surfaces ± dissimilar, abaxial ± grayish, rarely white, long hairs ± abundant especially on veins, 1 mm, weak, short hairs absent or sparse, cottony hairs absent, crisped hairs sparse to abundant, glands ± abundant, sometimes obscured, adaxial green to gray-green, long hairs sparse to abundant, loosely appressed, 0.5–1(–2) mm, short hairs absent or sparse, cottony and crisped hairs absent, glands ± abundant.
1–2.
(1–)3–12(–20)-flowered, congested, scarcely opening in fruit.
0.2–0.5 cm (proximal to 1.2 cm).
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 elliptic to linear, 1.5–3 × (0.3–)0.5–1.2 mm, lengths 1/2–3/4 times sepals, margins flat;
hypanthium 2.5–5 mm diam.;
sepals 2–5 mm, apex usually ± acute to obtuse, rarely acuminate, abaxial surfaces: venation faint, glands abundant, evident;
petals pale yellow, 2–5 × 2–4 mm, lengths ± equal to sepals;
filaments 0.5–2 mm, anthers 0.3–0.7 mm;
carpels 20–60, styles papillate-swollen in proximal 1/2–3/4+, 0.8–1.2 mm.
2 mm.
1 mm, smooth to faintly rugose.
Potentilla anserina
Potentilla jepsonii
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 jepsonii (a replacement name for P. pensylvanica var. ovium) is widespread at higher elevations in the Intermountain Region, extending into the Sierra Nevada in California and the Rocky Mountains in Idaho and Wyoming. Disjunct occurrences are known on the north rim of the Grand Canyon and San Francisco Peaks, Arizona, and Steens Mountain, Oregon. Collections have most commonly been included in P. pensylvanica (for example, B. Ertter 1993; N. H. Holmgren 1997b); they differ in leaf division, vestiture, and epicalyx bractlets. J. Soják considered var. ovium to be a variety of P. litoralis, which has comparable leaves and vestiture; P. jepsonii lacks the enlarged, revolute epicalyx bractlets that distinguish P. litoralis and is for the most part well separated geographically and elevationally. The exception is the montane phase of P. litoralis, which, at the current stage of knowledge, is somewhat arbitrarily delimited from P. jepsonii in the northern Rocky Mountains; collections from Waterton Lakes National Park in Alberta and the Okanogan Mountains in Washington are tentatively placed here in P. jepsonii.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
1. Epicalyx bractlets equal to or longer than sepals, often 2-fid or dentate; leaflet surfaces: abaxial with cottony-crisped hairs dense, long hairs common to abundant, on and between veins, adaxial glabrous or sparsely to densely hairy; achenes with dorsal groove; inland and seashore plants | → 2 |
1. Epicalyx bractlets shorter than sepals, usually entire, rarely 2-fid or dentate; leaflet surfaces: abaxial with cottony-crisped hairs absent or sparse to dense, long hairs absent or sparse, on veins, adaxial usually glabrous, rarely sparsely to densely hairy; achenes without dorsal groove; seashore or near-coastal plants | → 3 |
2. Hypanthium patelliform (wider than deep) in fruit; epicalyx bractlets narrowly to broadly ovate-triangular, equal to sepals; most of North America. | subsp. anserina |
2. Hypanthium turbinate (± as deep as wide) in fruit; epicalyx bractlets usually linear to elliptic, longer than sepals, rarely subequal; interior w Canada and Alaska. | subsp. yukonensis |
3. Carpels (20–)50–200(–250); leaves (3–)10–50(–75) cm; leaflets (4–)5–10(–15) per side, abaxial surfaces densely hairy, teeth (4–)6–12(–16) per side, teeth apices acute to acuminate, rarely subacute; flowers 1–2.5(–3.5) cm diam. | subsp. pacifica |
3. Carpels 25–60; leaves (1–)2–10 cm, rarely longer; leaflets 2–4(–5) per side, abaxial surfaces glabrous, sometimes sparsely to densely hairy, teeth 2–6(–10) per side, teeth apices rounded to subacute; flowers 0.8–1.5 cm diam. | subsp. groenlandica |
- Local floras:
BC, 
CA, 
OR, 
WA - Local Web sites: CalFlora, CalPhotos,
Flora NW, 
IL Wildflowers, 
MI Flora, 
MN Wildflowers, 
PNW Herbaria 
WildflowerSearch
iNaturalist (observations)
USDA Plants Database- LBJ Wildflower Center
- SEINet
- Plants of the World Online
- Encyclopedia of Life
- Wikipedia
- Google Image Search
- Local floras: CA, OR, WA
- Local Web sites: CalFlora, CalPhotos, Flora NW, PNW Herbaria
- WildflowerSearch
- iNaturalist (observations)
- LBJ Wildflower Center
- SEINet
- Plants of the World Online
- Encyclopedia of Life
- Wikipedia
- Google Image Search
