Potentilla bipinnatifida
Potentilla norvegica
bipinnate cinquefoil, potentille bipinnatifide, tansy cinquefoil
Norwegian cinquefoil, Norwegian or rough cinquefoil, potentille de norvège, rough cinquefoil
ascending to erect, (1–)2–5 dm.
ascending to erect, (0.5–)2–5(–9) dm, hairs at base ± stiff, tubercle-based, glands absent or sparse, inconspicuous.
ternate, rarely palmate, 3–15(–20) cm;
petiole 1–6(–10) cm, long hairs sparse to abundant, spreading to ascending, 1–2.5(–3) mm, usually ± stiff, ± crisped hairs absent or sparse to common, glands absent or sparse, inconspicuous;
leaflets 3(–5), at tip of leaf axis, separate to ± overlapping, largest ones broadly oblanceolate or elliptic to obovate, 1–6(–10) × 0.7–4(–5) cm, distal (1/2–)2/3–3/4+ of margin usually ± evenly incised 1/4–1/3 to midvein, teeth (3–)4–8(–15) per side, surfaces sparsely to moderately hairy, sometimes glabrate or abundantly hairy, glands mostly absent.
subpinnate to subpalmate, (6–)10–25 cm;
petiole (2–)5–15 cm, long hairs dense, appressed, 1–2 mm, soft to ± stiff, short hairs absent, crisped hairs sparse, glands absent, sparse, or obscured;
leaflets 2–3 per side, on distal 1/6–1/3(–1/2) of leaf axis, separate to ± overlapping, terminal ones oblanceolate, (2–)3–6(–10) × 1–2(–3.5) cm, margins revolute, incised 3/4+ to midvein, undivided medial blade 1.5–6 mm wide, teeth 5–8 per side, ± linear, surfaces ± to strongly dissimilar, abaxial usually white, rarely grayish, long hairs abundant especially on veins, 1–2 mm, ± weak, short hairs absent or obscured, cottony (and crisped) hairs ± dense, glands absent or obscured, adaxial green to grayish, long hairs sparse to abundant, loosely appressed, 0.5–1.5 mm, short hairs absent or sparse, crisped and/or cottony hairs sparse to common, glands sparse to common.
2–4.
(4–)10–50(–100)-flowered, congested or elongating in fruit.
5–40+-flowered.
0.2–0.8 cm (proximal to 2 cm).
(0.2–)0.5–2.5(–3) cm.
epicalyx bractlets narrowly elliptic to lanceolate, 2.5–6 mm, lengths ± 2/3 times sepals, margins flat;
hypanthium 3–5 mm diam.;
sepals 3–6 mm, apex ± acute, abaxial surfaces: venation indistinct, glands absent, sparse, or obscured;
petals yellow, 3–5 × 3–4 mm, lengths ± equal to sepals;
filaments 0.5–2 mm, anthers 0.3–0.5 mm;
carpels 50–80, styles papillate-swollen in proximal 1/2–3/4+, 1–1.2 mm.
epicalyx bractlets ± elliptic to narrowly ovate, (3–)4–8(–13) × 1.5–3(–5) mm;
hypanthium 4–7 mm diam.;
sepals 5–8 mm, apex acute to obtuse;
petals yellow, broadly obovate, (2–)3–5 × 2–4 mm;
stamens 15 or 20, filaments 0.7–2 mm, anthers 0.3–0.5 mm;
carpels 60–150, styles 0.7–0.8 mm.
1–1.2 mm, smooth to faintly rugose.
tan to brown, 0.8–1.3 mm, usually strongly rugose, without a corky protuberance.
= 56.
= 42, 56, 63, 70.
Potentilla bipinnatifida
Potentilla norvegica
Potentilla bipinnatifida is similar to P. litoralis in habit and leaf dissection but has flat, silky epicalyx bractlets and sepals with no evident glands. Vestiture is generally silkier, and the silvery to bicolor leaves are white-cottony abaxially. The two species are sympatric in the plains of Canada, with some intergradation; P. bipinnatifida is also common south to Colorado, where it is found in intermontane meadows and sagebrush flats. Outlying populations occur in Blaine and Custer counties, Idaho, and Duchesne and Piute counties, Utah. Eastern collections from disturbed sites might be adventive.
Potentilla missourica Hornemann ex Lindley and P. normalis Besser ex Sprengel are older names for this species; both were rejected against a conserved P. bipinnatifida with designated lectotypes (see J. Soják 2008b).
(Discussion copyrighted by Flora of North America; reprinted with permission.)
Potentilla norvegica is considered native in both North America and Eurasia, with the American race occasionally recognized as subsp. hirsuta for the stiff hairs on the stems, petioles, and pedicels of most plants in the flora area. This feature and other purported differences between the two races, in addition to being relatively subtle and inconstant, can be found in both America and Eurasia, though undoubtedly at least in part as introductions. Some populations in eastern Canada with glabrous stems have been distinguished as var. labradorica (for example, M. L. Fernald 1950), but such plants typically are intermixed with hairy individuals. The Löves (Á Löve 1954; Á Löve and D. Löve 1966) have argued that all three variants should be treated as distinct species due to chromosomal differences (hirsuta 2n = 56; labradorica 2n = 42; norvegica in the narrow sense 2n = 70) and obligate apomixis. Further research is needed to determine the taxonomic validity and rank of these expressions. If treated as species, P. flexuosa antedates P. labradorica (as noted by J. Soják 1969), while P. monspeliensis, although commonly used for the American race, is based on a European type (as summarized by A. Kurtto et al. in J. Jalas et al. 1972+, vol. 13).
An even greater challenge is determining native versus introduced ranges, especially given the likelihood that both native and Eurasian populations are widespread in North America. Achenes are produced prolifically and easily dispersed, to the extent that Potentilla norvegica is a contaminant in clover and hay fields and considered a weed at least in Canada (P. A. Werner and J. D. Soule 1976).
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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