Potentilla breweri
Potentilla bimundorum
Brewer's cinquefoil
cutleaf cinquefoil, potentille des deux mondes, staghorn cinquefoil
prostrate to ascending, (0.5–)1–3(–4.5) dm, lengths 2–4(–5) times basal leaves.
decumbent to ascending, rarely erect, 1–5 dm.
pinnate with distal leaflets ± confluent, (2–)4–12(–17) × 1–2.5(–5) cm;
petiole 1–3(–7) cm, straight hairs mostly absent, cottony hairs sparse to dense, glands absent or obscured to common;
primary lateral leaflets 3–6 per side, on distal 1/2–2/3(–3/4) of leaf axis, ± overlapping, largest ones cuneate-flabellate, 0.5–1.5(–2.5) × 0.4–2(–3) cm, distal 1/2 to whole margin unevenly incised 1/2 to completely to midvein (blade often medially split as well), ultimate teeth or segments 3–10, narrowly elliptic, 2–10(–15) × 1–3(–5) mm, apical tufts less than 1 mm, surfaces grayish green to white, not glaucous, straight hairs sparse to common (sparser adaxially), loosely appressed to ascending, 1–1.5 mm, soft, cottony hairs sparse to dense, glands sparse or obscured to common.
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.
1–3.
(1–)2–3.
2–15(–25)-flowered, openly cymose.
(5–)10–40+-flowered, ± congested to open.
(1–)1.5–2.5(–4) cm, straight in fruit.
0.3–1 cm (proximal to 3 cm).
epicalyx bractlets lanceolate to ovate, 2–5 × 1–1.5 mm;
hypanthium (3–)4–5 mm diam.;
sepals (3–)4–7 mm, apex acute;
petals 5–9(–10) × 4–8(–10) mm;
filaments (1–)2–4 mm, anthers (0.5–)1 mm;
carpels 15–25, styles 2–3 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.
1.8 mm, smooth, not carunculate.
1.3–1.5 mm, rugose.
= 72–73, 99, 100, 102.
= 28.
Potentilla breweri
Potentilla bimundorum
Of conservation concern.
Potentilla breweri differs from other members of sect. Multijugae in its often dense, cottony vestiture. Density of cottony hairs and leaflet dissection can differ significantly between first-formed and mid- to late-season leaves of P. breweri; in the description above, leaves are those predominant at anthesis.
Potentilla breweri is most common in the Sierra Nevada of California, with sporadic occurrences to the Cascade Range in southern Washington. Disjunct populations occur in the Ruby and Snake ranges in Nevada and on Steens Mountain in Oregon, where often introgressed with P. versicolor. Reports from Utah are based on collections of P. concinna var. proxima or possible hybrids between P. concinna var. proxima and P. ovina var. decurrens.
J. Clausen et al. (1940) concluded that Potentilla breweri (with P. versicolor as synonym) belonged with P. bruceae and P. drummondii as members of a cenospecies that probably also included unnamed species (possibly P. ovina var. decurrens) from the mountains of Colorado, Utah, and Wyoming. Chromosome number varied within populations, and high numbers of univalents were present.
Recognition of Potentilla breweri as a distinct species differs from recent treatments in which it was considered to be a variety or subspecies of P. drummondii, parallel to the treatment of P. bruceae. The present continental perspective of the genus, as well as additional fieldwork, has resulted in the return of all three to species rank (B. Ertter and D. Mansfield 2007). Placement of P. breweri in sect. Multijugae, separate from P. bruceae and P. drummondii in sect. Graciles, is based on the commonly prostrate habit, fully pinnate leaves, and deeply divided overlapping leaflets.
Although B. C. Johnston (1980) used Potentilla breweri var. viridis Jepson to accommodate greener-than-average sparsely cottony plants, including populations treated here as P. versicolor, the type is probably a sterile hybrid with P. wheeleri as one parent (B. Ertter 1992). The type of P. millefolia var. algida Jepson (included by Johnston in the synonymy of var. viridis) and comparable plants from north-central California combine features of P. breweri and P. versicolor but are more glandular than either. This variant, as well as exceptionally small plants from the Warner Mountains of California, may prove distinct.
(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.)
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