Potentilla rivalis
Potentilla albiflora
brook cinquefoil, brook or river cinquefoil, river cinquefoil, streambank cinquefoil
Pinaleño cinquefoil, whiteflower 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.
0.2–1.5 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.
ternate, 1.5–10 cm;
petiole 1–7 cm, long hairs ± abundant, spreading to ascending, 0.5–1(–1.5) mm, weak to stiff, glands sparse to abundant;
leaflets 3, central obovate, 0.5–2.5(–3.5) × 0.4–1.3(–2) cm, not to scarcely petiolulate, distal 1/2–2/3 of margins evenly incised ± 1/3 to midvein, teeth 3–5(–6) per side, surfaces green, long hairs ± abundant, 0.5–1 mm, glands sparse to abundant.
(5–)20–100+-flowered.
1–5(–10)-flowered.
0.2–1(–2) cm.
0.5–2 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.
epicalyx bractlets lanceolate-elliptic, (1.5–)2–3(–5) × 0.5–1.5 mm;
hypanthium 3.5–6 mm diam.;
sepals 3–6(–8) mm, apex acute;
petals ± paler abaxially, bright yellow adaxially, narrowly obcordate, (3–)4–7(–8) × 3–5 mm;
filaments 2–4 mm, anthers 0.5–1 mm;
carpels 10–25, styles 2–3 mm.
yellowish, 0.7–0.9 mm, ± smooth, without a corky protuberance.
1.5 mm, smooth.
hairs not well differentiated from long hairs, absent or sparse throughout.
= 14, 70.
Potentilla rivalis
Potentilla albiflora
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 albiflora grows on the Pinaleño (Graham) Mountains in Graham County, with a few outlying collections known from the Mogollon Rim in Greenlee County and the Santa Catalina Mountains of Pima County.
Contrary to the specific epithet, petals of living plants are yellow, not white; like those of many Potentilla species, they tend to fade in pressed material.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
- Local floras:
BC, 
CA, 
OR, 
WA - Local Web sites: CalFlora, CalPhotos,
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MD Biodiversity, 
MN Wildflowers, 
MO Plants, 
PNW Herbaria, Turner Photog. 
WildflowerSearch
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