Potentilla rivalis
Potentilla fragiformis
brook cinquefoil, brook or river cinquefoil, river cinquefoil, streambank cinquefoil
strawberry 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.
ascending to erect, 0.3–1.5(–2) dm, lengths 1–2 times basal leaves.
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.
not in ranks, ternate, (1–)4–10(–15) cm;
stipules: apex acute to obtuse;
petiole (0.3–)2–11(–13) cm, long hairs abundant, ascending to spreading, 1–2.3 mm, soft, glands sparse to common;
leaflets 3, central obovate, 0.7–2.5 × 0.5–1.6 cm, petiolule 0–1 mm, margins revolute, not lobed, distal 1/2–2/3 evenly incised ± 1/3 to midvein, teeth 2–3(–4) per side, surfaces ± similar, green (paler abaxially), hairs common, 1–1.5 mm, glands common (sparser adaxially).
(5–)20–100+-flowered.
1–3-flowered.
0.2–1(–2) cm.
straight, 0.5–2 cm in flower, to 3.5 cm in fruit.
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.
epicalyx bractlets oblong, 3–7 × 1.2–2.5 mm, margins revolute;
hypanthium 4–6 mm diam.;
sepals 4–6(–7) mm, apex broadly acute to obtuse;
petals yellow, 9–12 × 8–10 mm;
filaments (2–)2.8–3.2 mm, anthers 0.5–0.8 mm;
carpels 40–50, styles filiform, not or scarcely papillate-swollen proximally, 1.7–2 mm.
yellowish, 0.7–0.9 mm, ± smooth, without a corky protuberance.
1.3–1.5.
= 14, 70.
= 42, 56 (Russian Far East).
Potentilla rivalis
Potentilla fragiformis
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.)
Recent collections of Potentilla fragiformis in Alaska on the coast of the Bering and Chukchi seas have confirmed historical reports (P. A. Rydberg 1908d) of this Beringian species in North America. Dwarf plants from St. Lawrence Island are somewhat intermediate to P. nana but have the larger petals and longer styles of P. fragiformis.
(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, 
KS Wildflowers, 
MD Biodiversity, 
MN Wildflowers, 
MO Plants, 
PNW Herbaria, Turner Photog. 
WildflowerSearch
iNaturalist (observations)
USDA Plants Database- LBJ Wildflower Center
- SEINet
- Plants of the World Online
- Encyclopedia of Life
- Wikipedia
- Google Image Search
