Potentilla rivalis
Potentilla villosa
brook cinquefoil, brook or river cinquefoil, river cinquefoil, streambank cinquefoil
hairy cinquefoil, northern cinquefoil, villous cinquefoil
stout, sometimes short-columnar, not sheathed with marcescent whole 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.
ascending, 0.5–2(–2.5) dm, lengths 1.5–3 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.
2–12(–15) cm;
petiole 1–9(–12) cm, long hairs ± abundant to dense, spreading to ascending, 1–2.5(–3) mm, soft to weak, smooth, crisped hairs absent or sparse, cottony hairs absent, glands sparse to common, sometimes obscured;
leaflets usually ± overlapping, central broadly obovate to suborbiculate, (0.5–)1.5–2.5(–3) × (0.5–)1.5–2.6(–3.2) cm, sessile to subsessile, base cuneate to rounded, margins revolute, distal 1/2–2/3(–3/4) incised 1/4–1/2 to midvein, teeth 3–6(–7) per side, ± approximate to ± distant, surfaces ± dissimilar, abaxial yellowish or grayish white, long hairs 1–2 mm, cottony-crisped hairs ± dense, adaxial grayish green, long hairs abundant to dense, crisped hairs absent, sparse, or obscured.
(0–)1–2.
(5–)20–100+-flowered.
(1–)2–7(–10)-flowered.
0.2–1(–2) cm.
0.5–3(–4) cm in flower, to 4 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 ovate to oval-elliptic, 3–8 × 2–5 mm, 2/3 to as wide as sepals, margins strongly revolute, red glands absent;
hypanthium 5–7 mm diam.;
sepals 4–8 mm, apex ± acute;
petals (5–)7–15 × 7–16 mm, significantly longer than sepals;
filaments 1.8–2.1 mm, anthers 0.7–0.8 mm;
carpels 150–250, apical hairs usually absent, rarely present (cottony), styles narrowly conic to tapered, ± papillate-swollen on proximal 1/5–1/2, 0.9–1.1 mm.
yellowish, 0.7–0.9 mm, ± smooth, without a corky protuberance.
0.9–1.3 mm.
= 14, 70.
= 14.
Potentilla rivalis
Potentilla villosa
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 villosa is the only documented diploid species of sect. Niveae in North America and, almost certainly, it is fully sexual. It is a characteristic species of coarse-grained beaches and coastal cliffs from southwestern British Columbia to western Alaska and the Russian Far East, and also occurs on scattered mountains in the Olympic Peninsula and Cascade Range of Washington and Oregon (providing the higher elevational extreme). These southern populations, which have been called var. parviflora, tend to be smaller, more delicate, less hairy plants in general, with fewer and smaller flowers. At least some plants in some southern populations also have cottony hairs on the carpels.
(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
- Local floras: BC, OR, WA
- Local Web sites: Flora NW, PNW Herbaria
- WildflowerSearch
- iNaturalist (observations)
- USDA Plants Database
- LBJ Wildflower Center
- SEINet
- Plants of the World Online
- Encyclopedia of Life
- Wikipedia
- Google Image Search
