Potentilla ovina
Potentilla rivalis
sheep cinquefoil
brook cinquefoil, brook or river cinquefoil, river cinquefoil, streambank cinquefoil
prostrate to ascending, (0.3–)0.8–2(–3.5) dm, lengths (1–)1.5–3 times basal leaves.
decumbent to erect, sometimes prostrate, (0.5–)1–4(–7) dm, hairs at base not stiff, not tubercle-based, glands absent or sparse, inconspicuous.
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.
pinnate with distal leaflets ± distinct, (1.5–)2–10(–13) × 0.7–3.5(–5) cm;
petiole 0.5–3.5(–5) cm, straight hairs sparse to abundant, sometimes absent (var. decurrens), ± appressed to ascending, 1 mm, ± stiff, cottony hairs absent, glands sparse, often obscured;
primary lateral leaflets 3–6 per side (often with additional interspersed leaflets), on distal 1/2–2/3(–3/4) of leaf axis, ± separate to ± overlapping, largest ones narrowly cuneate-oblanceolate to ± obovate, (0.3–)0.5–2(–3.5) × (0.2–)0.3–0.8(–1) cm, distal 1/4 to whole margin unevenly to pinnately (at least distal leaflets of var. ovina) incised 1/2–3/4+ to midvein, ultimate teeth 2–9(–11), linear or oblong to ovate, 1–7(–9) × 1–2 mm, apical tufts 0.5–2 mm, surfaces green to grayish, not glaucous, straight hairs sparse to abundant (sparser adaxially), sometimes absent (except on margins), loosely appressed, 0.5–2 mm, ± stiff, cottony hairs absent, crisped hairs sometimes sparse to common, glands absent or inconspicuous.
1–2.
(1–)2–11(–20)-flowered, usually openly cymose.
(5–)20–100+-flowered.
(0.8–)1–2(–4) cm, straight to ± recurved in fruit.
0.2–1(–2) cm.
epicalyx bractlets linear-lanceolate to narrowly elliptic, sometimes doubled, 2–3.5(–5) × 1 mm;
hypanthium 3–5 mm diam.;
sepals 3.5–5.5(–7) mm, apex acute to obtuse;
petals 4–7(–8) × 3.5–8 mm;
filaments 1–2.5 mm, anthers 0.4–1 mm usually ± 1/2 as long as filaments;
carpels 10–20, styles 2–3 mm.
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.
1.5–2 mm, smooth, not carunculate.
yellowish, 0.7–0.9 mm, ± smooth, without a corky protuberance.
= 14, 70.
Potentilla ovina
Potentilla rivalis
Varieties 2 (2 in the flora).
Potentilla ovina is here accepted as an implicit new name by J. M. Macoun for P. diversifolia var. pinnatisecta, in agreement with N. H. Holmgren (1997b). In contrast, B. C. Johnston (1980) considered the names heterotypic. Potentilla ovina has priority at the species rank over P. pinnatisecta by one month.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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.)
1. Distal leaflets: ± whole margin pinnately incised 3/4+ to midvein, teeth 4–9(–11), linear, surfaces grayish, rarely green, hairs sparse to dense. | var. ovina |
1. Distal leaflets: distal 1/4–1/2(–3/4) of margin unevenly to pinnately incised 1/2–2/3(–3/4) to midvein, teeth 2–5(–7), ovate to oblong, surfaces green, hairs absent (except on margins) or sparse. | var. decurrens |
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BC, 
CA, 
OR, 
WA - Local Web sites: CalFlora, CalPhotos,
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IL Wildflowers, 
KS Wildflowers, 
MD Biodiversity, 
MN Wildflowers, 
MO Plants, 
PNW Herbaria, Turner Photog. 
WildflowerSearch
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USDA Plants Database- LBJ Wildflower Center
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