Potentilla rivalis
Potentilla crantzii
brook cinquefoil, brook or river cinquefoil, river cinquefoil, streambank cinquefoil
alpine cinquefoil, potentille de crantz
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, 0.5–2(–3) 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-ranked, usually palmate, sometimes ternate, 2–10(–15) cm;
stipules: apex obtuse to truncate, rarely acute;
petiole 0.5–6.5(–10) cm, long hairs usually ± sparse, usually ± ascending, sometimes spreading or appressed, 1–2.5 mm, weak to ± stiff, glands absent or sparse;
leaflets 3–5, central obovate, 1.5–3(–3.5) × 0.8–1.5(–2) cm, petiolule 0–1 mm, margins flat, not lobed, distal 1/2–2/3 evenly incised 1/3–1/2 to midvein, teeth 3–4(–5) per side, not secondarily toothed, surfaces similar, green, not glaucous, hairs absent or sparse, rarely common, 0.8–1.5 mm, glands absent or sparse to abundant (fewer adaxially).
(5–)20–100+-flowered.
(2–)3–8(–12)-flowered.
0.2–1(–2) cm.
straight, 1–3(–4) cm in flower, to 6 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 or narrowly ovate, (1.5–)2.5–4 × (0.8–)1–1.3 mm, margins flat;
hypanthium 3–4 mm diam.;
sepals (3–)4–5(–6) mm, apex broadly acute;
petals yellow, 4–7(–9) × 4–8 mm;
filaments 1.8–2.2 mm, anthers 0.3–0.6 mm;
carpels 30–40, styles columnar-filiform, not papillate-swollen proximally, 1–1.6 mm.
yellowish, 0.7–0.9 mm, ± smooth, without a corky protuberance.
1.2 mm.
= 14, 70.
= 42; 28, 35, 49 (Europe).
Potentilla rivalis
Potentilla crantzii
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 crantzii is primarily European, not restricted to coasts as in North America. The nomenclatural history is long and complex (A. Kurtto et al. in J. Jalas et al. 1972+, vol. 13), with P. alpestris and P. maculata in greatest historical use. The name P. ×protea Soják is available for presumed hybrids between P. crantzii and P. hyparctica.
The emphasis on two-ranked leaves to distinguish Potentilla crantzii from P. verna follows J. Soják (pers. comm.). Some collections of P. crantzii from Newfoundland approach P. verna in their more elongate caudex branches and shorter stature.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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