Potentilla breweri
Potentilla furcata
Brewer's cinquefoil
fork cinquefoil
usually not sheathed with marcescent whole leaves.
prostrate to ascending, (0.5–)1–3(–4.5) dm, lengths 2–4(–5) times basal leaves.
ascending to erect, (0.5–)1–3 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.
often both ternate and palmate on same plant, sometimes subpalmate, 4–10 cm;
petiole 2.5–8 cm, long hairs common to abundant, loosely appressed to ascending-spreading, 1–2 mm, weak to ± stiff, ± verrucose, short and/or crisped hairs sparse to abundant, cottony hairs absent, glands sparse to common;
leaflets 3–5, proximalmost separated by 0(–2) mm, central oblong to obovate, 1.4–2.5(–5) × 0.6–1.3(–2) cm, petiolules 1–3(–5) mm, distal 2/3–3/4 of margin incised 1/2–3/4+ to midvein, teeth 3–5 per side, 3.5–6 mm, apical tufts 0.5–1 mm, abaxial surfaces grayish white to white, long hairs common to abundant, cottony-crisped hairs usually dense, short hairs and glands absent or obscured, adaxial green to grayish green, long hairs sparse to common, 0.5–1(–1.5) mm, ± stiff, short and/or crisped hairs sparse to common, sometimes abundant, cottony hairs absent, glands sparse to abundant.
1–3.
1–3.
2–15(–25)-flowered, openly cymose.
7–12(–20)-flowered, ± open, branch angle 5–30(–50)°.
(1–)1.5–2.5(–4) cm, straight in fruit.
(0.5–)1–2 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 lanceolate, 2–3.5 × 0.6–1 mm;
hypanthium 2.5–3.5 mm diam.;
sepals 2.5–4 mm, apex subacute to acute, glands ± common, usually not obscured;
petals pale yellow, not overlapping, 3–5(–6) × 3–4(–5) mm, slightly longer than sepals;
filaments 0.8–1.8 mm, anthers 0.4 mm;
carpels 30–60, styles 0.7–0.9 mm.
1.8 mm, smooth, not carunculate.
1.2 mm.
= 72–73, 99, 100, 102.
Potentilla breweri
Potentilla furcata
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 furcata is a characteristic species of the steppe bluffs of interior and south-central Alaska, Yukon, and northern British Columbia, mainly within the unglaciated Beringian region. It differs from P. rubricaulis in having less open inflorescences, smaller flowers, narrower petals, more papillae on styles, and denser glands on epicalyx and calyx.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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