Potentilla rivalis
Potentilla saximontana
brook cinquefoil, brook or river cinquefoil, river cinquefoil, streambank cinquefoil
Rocky 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.
(0.2–)0.4–1(–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.
subpalmate to pinnate, (1–)1.5–4(–7) cm;
petiole 0.5–2(–4) cm, vestiture not or scarcely seasonally dimorphic, long hairs abundant to dense, appressed to spreading, 1–1.5(–2) mm, weak to ± stiff, cottony hairs usually absent, crisped hairs absent or sparse, glands sparse;
leaflets 3 at tip of leaf axis plus 1–2(–3) additional pairs separated from tip by 1–5 mm, on distal 1/10–1/3 of leaf axis, largest leaflets obovate to oblanceolate, 0.5–1.5 × 0.3–1.2 cm, ± whole margin incised 1/2–3/4 to midvein, teeth 2–4(–5) per side, separate to overlapping, 1–4 mm, surfaces ± dissimilar, abaxial grayish green to white, straight hairs abundant, 1–1.5 mm, cottony and crisped hairs sparse to dense, rarely absent, glands sparse or obscured, adaxial green to grayish, straight hairs sparse to abundant, 1–2 mm, cottony hairs absent or rarely sparse, crisped hairs absent or sparse, glands ± sparse.
0–1(–2).
(5–)20–100+-flowered.
(1–)2–5(–10)-flowered.
0.2–1(–2) cm.
0.5–1.5 cm (proximal to 2.5 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 ± ovate-elliptic, 2–4 × 1–1.5 mm;
sepals 3.5–5 mm, apex bluntly acute;
petals 4–6(–8) × 4–7 mm;
filaments 0.5–2 mm, anthers 0.5 mm;
carpels 10–20+, styles columnar-filiform, papillate-swollen at base, if at all, 0.8–1.5 mm.
yellowish, 0.7–0.9 mm, ± smooth, without a corky protuberance.
1.5 mm.
= 14, 70.
Potentilla rivalis
Potentilla saximontana
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 saximontana is a small plant of very high elevations in the mountains of Colorado, the La Sal and Uinta mountains of Utah, and the Absaroka and Beartooth mountains of Wyoming and Montana. Although sometimes confused with P. rubricaulis (for example, W. A. Weber and R. C. Wittman 1996), the subpinnate leaves, open few-flowered inflorescences, and columnar-filiform styles make P. saximontana a distinct species.
The lectotype of Potentilla nivea Linnaeus var. dissecta S. Watson [= P. saximontana var. dissecta (S. Watson) Soják] has been tentatively included in P. saximontana (B. Ertter 2008), but P. saximontana is not otherwise known from the Canadian Rockies. See B. Ertter et al. (2013) for additional discussion.
The combination Potentilla rubripes Rydberg var. saximontana (Rydberg) Th. Wolf is incorrect, in that P. saximontana is the older name.
(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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