Potentilla thurberi
Potentilla bimundorum
scarlet cinquefoil, Thurber's cinquefoil
cutleaf cinquefoil, potentille des deux mondes, staghorn cinquefoil
(2–)3–7(–10) dm.
decumbent to ascending, rarely erect, 1–5 dm.
palmate, (2–)4–15(–30) cm;
petiole (2–)3–10(–25) cm, long hairs sparse to common, spreading, 1–3.5 mm, weak, glands sparse to abundant, sometimes absent;
leaflets 5(–7), at tip of leaf axis, central one (1–)2–6(–8) × (0.5–)1–2.5(–4) cm, petiolules 0(–10) mm, distal 3/4 to whole margin incised 1/5–1/4 to midvein, teeth (4–)7–15(–19) per side (sometimes secondarily toothed), (1–)2–3(–5) mm, teeth apex acute to ± obtuse, surfaces slightly to strongly dissimilar, abaxial pale green to white, straight hairs sparse to abundant, often dense on veins, 0.5–3 mm, cottony hairs absent or sparse to dense, glands ± sparse or absent, sometimes obscured, adaxial green, straight hairs sparse to abundant, 0.2–1 mm, cottony hairs absent, glands ± sparse or absent.
subpinnate, 7–22(–25) cm;
petiole 3–12(–15) cm, long hairs ± abundant, appressed to ascending, 0.5–3 mm, stiff, short hairs absent, cottony or crisped hairs absent, glands absent or sparse;
leaflets 3(–4) per side, on distal 1/5–1/3(–1/2) of leaf axis, overlapping or not, terminal ones oblong to broadly oblong, 1.5–5 × 0.7–2 cm, margins strongly revolute, incised nearly to midvein, undivided medial blade 1–3 mm wide, teeth (3–)4–5 per side, linear, rarely narrowly oblong to narrowly lanceolate, surfaces strongly dissimilar, abaxial white or grayish white, long hairs abundant, ± 1 mm, stiff verrucose on veins, sparse and soft between veins, short hairs absent, crisped and cottony hairs dense, glands absent, adaxial dark green, long hairs sparse to common, tightly appressed, 0.5–1 mm, short hairs absent, cottony and crisped hairs absent, glands absent or sparse.
stipules usually toothed, sometimes entire.
(1–)2–3.
(4–)10–35-flowered.
(5–)10–40+-flowered, ± congested to open.
0.5–4 cm.
0.3–1 cm (proximal to 3 cm).
epicalyx bractlets narrowly to broadly lanceolate-elliptic (rarely toothed or lobed), 4–9(–14) × (1–)1.5–2 mm;
sepals 4–10(–15) mm, apex acute to acuminate;
petals ± dark reddish throughout, (3.5–)6–10 × 6–10 mm;
filaments 1.5–3 mm, anthers 0.8–1 mm;
carpels 30–70, styles 2.5–3.5 mm.
epicalyx bractlets linear to narrowly oblong-lanceolate, 3–5 × 0.9–1.3 mm, lengths ± 3/4 times sepals, margins flat;
hypanthium 2.5–3.5 mm diam.;
sepals 4–7(–8) mm, apex acute to obtuse, abaxial surfaces: venation prominent at least proximally, glands ± sparse, obscured to evident;
petals pale yellow, 3.5–5 × 3–5 mm, lengths ± equal to sepals;
filaments 0.5–1.5 mm, anthers 0.5–0.6 mm;
carpels 40–60, styles papillate-swollen at very base, if at all, 0.8–0.9 mm.
1.5 mm, ± rugose.
1.3–1.5 mm, rugose.
= 28.
Potentilla thurberi
Potentilla bimundorum
Varieties 2 (2 in the flora).
The abaxially white-cottony leaflets of var. atrorubens usually make it easily distinguished from var. thurberi, which lacks cottony hairs and is usually less hairy in general. The two varieties sometimes occur together and intermediates between the extremes are common.
The degree of glandularity and the lengths of the central leaflets are greater in the southern populations of both varieties. The glands are less widely distributed on the plants northward and are fewer in northern Arizona and New Mexico. Leaflets are shorter and broader north of Graham County, Arizona, and Otero County, New Mexico.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
Potentilla bimundorum is the correct name for what has been treated as P. multifida Linnaeus in North America. It is the only American representative of the mainly Eurasian P. multifida group, which is sometimes treated as a distinct section. J. Soják (2005) presented a useful survey and key to this group, showing that its species, in spite of being merged within P. multifida in the broad sense by many authors, are each distinct and with their own range. Potentilla multifida in the narrow sense is restricted to eastern Europe and western Siberia.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
1. Leaflets pale green abaxially, cottony hairs absent. | var. thurberi |
1. Leaflets ± white to white abaxially, cottony hairs sparse to dense. | var. atrorubens |
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