Potentilla rivalis
Potentilla anglica
brook cinquefoil, brook or river cinquefoil, river cinquefoil, streambank cinquefoil
English cinquefoil, potentille d'angleterre, trailing cinquefoil, trailing tormentil, wood cinquefoil
decumbent to erect, sometimes prostrate, (0.5–)1–4(–7) dm, hairs at base not stiff, not tubercle-based, glands absent or sparse, inconspicuous.
soon becoming prostrate, ± flagelliform, usually openly branched, eventually rooting at some nodes, (0.3–)1.5–7+ dm.
ternate, palmate, or subpalmate (with distal leaflets ± confluent), basal 3–15(–25) cm, cauline 2–7(–12) cm;
petiole: basal 1–9(–16) cm, cauline 0.5–4(–8) cm, long hairs usually common to abundant, ascending to spreading, 0.5–1.5 mm, usually ± weak, ± crisped hairs common to abundant, glands absent or sparse, inconspicuous;
leaflets 3–5(–7), at tip to distal 1/5 (basal) or 1/2 (cauline) of leaf axis, separate to ± overlapping, largest ones oblanceolate-elliptic to obovate, (0.5–)1–5(–6) × 0.5–2(–2.5) cm, distal 1/2–3/4 of margin evenly to unevenly incised 1/3–1/2 to midvein, sometimes cleft nearly to base, teeth 3–8 per side, surfaces moderately to abundantly hairy, glands absent or sparse.
± persistent, ternate or palmate, 2–10(–12) cm;
petiole 1–7(–8) cm, long hairs sparse to abundant, appressed, 0.5–1 mm, stiff, glands absent;
leaflets 3–5, central ± obovate to cuneate, 1–3(–3.5) × 0.8–2(–2.5) cm, distal ± 1/2 of margin incised 1/4–1/3(–1/2) to midvein, teeth 2–4 per side, surfaces similar, green, sparsely to moderately hairy.
2–3(–4) proximal to 1st flowering or branching node, usually well expanded at anthesis, usually ternate, 2–6(–10) cm;
petiole 0.3–4(–8) cm;
leaflets (3–)5, ± resembling or narrower than those of basal leaves, narrowly cuneate, 1–2(–3.5) × 0.8–2(–2.5) cm, apex rounded to obtuse.
(5–)20–100+-flowered.
solitary flowers at stolon nodes.
0.2–1(–2) cm.
(1–)3–10(–17) cm.
epicalyx bractlets narrowly elliptic to ovate, (1.5–)2–4(–6) × 0.8–1.5 mm;
hypanthium (2–)3–5 mm diam.;
sepals 3–5 mm, apex broadly acute to obtuse;
petals pale yellow to yellow, broadly oblong-obovate, 1.5–2 × 1 mm;
stamens (5–)10(–15), filaments 0.4–0.9 mm, anthers 0.2–0.3 mm;
carpels 40–100, styles 0.5–0.6 mm.
4(–5)-merous;
epicalyx bractlets narrowly elliptic to oblong or ovate, 3–4(–7) × 1–1.5 mm, smaller than to slightly larger than sepals;
hypanthium 2–4 mm diam.;
sepals (3–)4–6 mm, apex broadly acute or acuminate;
petals 6–9 × 5–9 mm, apex ± retuse;
stamens 15–20, filaments 0.8–1.2 mm, anthers 0.8–1.2 mm;
carpels 20–50, styles 0.9–1.5 mm.
yellowish, 0.7–0.9 mm, ± smooth, without a corky protuberance.
1–1.5(–1.8) mm, ± smooth.
± erect, stout to slender, 1–4 cm.
= 14, 70.
= 28, 56 (Europe).
Potentilla rivalis
Potentilla anglica
Potentilla rivalis is most abundant in central and western North America; reports of occurrences in more eastern states (including those listed here) need confirming, as P. rivalis and P. norvegica often have been confused. Potentilla leucocarpa Rydberg was provided as a superfluous replacement name for P. millegrana; specimens annotated by Rydberg with this name include both P. biennis and P. rivalis.
Potentilla rivalis is sometimes divided into three species or varieties (for example, H. J. Scoggan 1978–1979). In a strict sense, var. rivalis has subpalmately compound (5-foliate) leaves. Variety milligrana, the most common phase, has 3-foliate leaves. Plants with both 3- and 5-foliolate leaves are var. pentandra, which also tends to have five stamens, though this latter character is not correlated with the leaf features. On the Great Plains, where var. pentandra is confined, all three expressions are often found in a single population (R. L. McGregor 1986b).
(Discussion copyrighted by Flora of North America; reprinted with permission.)
Potentilla anglica apparently is a product of hybridization involving P. erecta and P. reptans (B. Matfield and J. R. Ellis 1972) that has become stabilized and distinct from both parents. In Europe, it forms back-cross hybrids with both P. erecta (P. ×suberecta Zimmeter) and P. reptans (P. ×mixta Nolte); these hybrids are not known from North America. A garden hybrid supposedly between P. anglica and P. nepalensis Hooker (known as P. ×tonguei Mallett) was found in Allegany State Park, New York, but this was likely cultivated rather than naturalized.
Potentilla anglica probably was introduced even in Newfoundland (A. Kurtto et al. in J. Jalas et al. 1972+, vol. 13), contrary to the view expressed by M. L. Fernald (1950).
The name Potentilla procumbens Sibthorp was previously used for this species; that is a superfluous and illegitimate name.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
- Local floras:
BC, 
CA, 
OR, 
WA - Local Web sites: CalFlora, CalPhotos,
Flora NW, 
Go Botany, 
IL Wildflowers, 
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MD Biodiversity, 
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WildflowerSearch
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- Local floras: BC, CA, OR
- Local Web sites: CalFlora, CalPhotos, Flora NW, Go Botany, PNW Herbaria
- WildflowerSearch
- iNaturalist (observations)
- USDA Plants Database
- LBJ Wildflower Center
- SEINet
- Plants of the World Online
- Encyclopedia of Life
- Wikipedia
- Google Image Search
