Potentilla rivalis
Potentilla robbinsiana
brook cinquefoil, brook or river cinquefoil, river cinquefoil, streambank cinquefoil
dwarf mountain cinquefoil, Robbins' cinquefoil, White Mountains 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.
spreading to erect, 0.1–0.4 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, 1–2 cm;
stipules: apex broadly acute;
petiole 0.7–3 cm, long hairs sparse to abundant, spreading to subappresed, 0.2–2 mm, weak, glands sparse to common;
leaflets 3, central obovate, 0.5–1.3 × 0.2–1 cm, petiolule 0–1 mm, margins flat to ± revolute, not lobed, distal ± 2/3 evenly incised ± 1/2 to midvein, teeth 2–4(–5) per side, surfaces similar, green, hairs ± abundant (or nearly absent adaxially), 0.5–1 mm, glands sparse to common.
(5–)20–100+-flowered.
1(–2)-flowered.
0.2–1(–2) cm.
straight, 0.5–3 cm, not much longer in fruit than in flower.
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 to elliptic, (1.8–)2–2.5(–3) × 0.7–1.2(–1.4) mm, ± equal to sepals, margins flat to ± revolute;
hypanthium (4–)5–7 mm diam.;
sepals (1.8–)2–2.5(–3) mm, apex broadly acute;
petals yellow, 2–3 × 2–3 mm;
filaments 0.5–1 mm, anthers 0.4–0.6 mm;
carpels 20–30, styles columnar-tapered, sometimes ± papillate-swollen in proximal 1/3–1/2, 0.8–1 mm.
yellowish, 0.7–0.9 mm, ± smooth, without a corky protuberance.
1–1.3 mm.
= 14, 70.
= 49.
Potentilla rivalis
Potentilla robbinsiana
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.)
Of conservation concern.
Potentilla robbinsiana is known only from two sites in the White Mountains, Monroe County, New Hampshire, and is reported in Vermont. Additional populations have been established nearby as a result of transplant efforts. Listed in 1980 as a federally endangered species, an intense recovery program resulted in the species being delisted in 2002.
Some early specimens were distributed as Potentilla frigida Villars, a similar European species.
(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
