Potentilla subjuga
Potentilla brunnescens
Colorado cinquefoil
brownish cinquefoil, slender brown cinquefoil, slender cinquefoil
conspicuous, usually golden.
(0.8–)1–2.5(–3.5) dm.
ascending to nearly erect, (1.5–)3–7 dm.
usually palmate with additional lateral leaflets, sometimes pinnate, 3–10(–14) cm;
petiole 1.5–5 cm, vestiture seasonally dimorphic, long hairs abundant, spreading on first-formed leaves, tightly appressed to ascending on later-formed leaves, 1–2 mm, ± stiff (especially on later-formed leaves), cottony and crisped hairs usually absent, glands absent or sparse;
leaflets (3–)5 at tip of leaf axis plus 1(–2) additional pair(s) separated from tip by 3–20 mm, on distal 1/10–1/3(–1/2) of leaf axis, largest leaflets oblanceolate-oblong, (0.5–)1.5–2.5(–3) × 0.3–1 cm, ± whole margin incised 1/2–2/3(–3/4) to midvein, teeth (2–)4–9 per side, usually touching to strongly overlapping, sometimes separate, 2–6 mm, surfaces usually strongly dissimilar (less so on first-formed leaves), abaxial usually white, straight hairs ± abundant (mostly on veins), 1–2 mm, cottony or crisped/cottony hairs ± dense (sparser on first-formed leaves), glands absent or obscured, adaxial green (to grayish), straight hairs sparse to common, 0.5–1.5 mm, cottony and crisped hairs absent, glands sparse.
sometimes 2-ranked, palmate, (5–)10–30 cm;
petiole (1.5–)5–25(–50) cm, long hairs sparse to abundant, appressed to spreading, 1–2 mm, ± stiff, short, crisped, and cottony hairs absent, glands ± abundant;
leaflets (5–)7–9, at tip of leaf axis, separate to slightly overlapping, largest ones oblanceolate-elliptic to narrowly obovate, (2–)5–10 × 1–4 cm, margins flat to ± revolute, distal 3/4 to nearly whole length ± evenly incised (1/4–)1/2–3/4+ to midvein, undivided medial blade 2–15(–20) mm wide, teeth (5–)7–10 per side, linear to broadly lanceolate, 3–15 mm, surfaces ± similar, abaxial paler, green, not glaucous, long hairs sparse to common, short-crisped hairs absent or sparse, cottony hairs absent, glands ± abundant.
1–3.
1–3(–4).
3–20(–30)-flowered.
12–30(–70)-flowered.
0.5–2 cm (proximal to 3 cm).
0.2–1(–4) cm.
epicalyx bractlets narrowly to broadly lanceolate, 2–5(–6) × 1–1.5 mm;
sepals 4–7 mm, apex acute to acuminate;
petals 4–8 × 4–8 mm;
filaments (0.5–)1–2 mm, anthers 0.3–0.8 mm;
carpels 15–30, styles filiform to filiform-tapered, ± papillate-swollen in less than proximal 1/5, 1.5–2 mm.
epicalyx bractlets lanceolate to elliptic, 3–6 × 1–2 mm, hairs sparse to common, loosely appressed to spreading, glands common to abundant;
hypanthium 4–6(–8) mm diam.;
sepals 4–8(–9) mm, apex acute to acuminate;
petals 6–9 × 6–10 mm;
filaments 1–2 mm, anthers 0.6–1 mm;
carpels 30–60, styles filiform-tapered, papillate-swollen proximally, 1.5–2 mm.
1.2–1.6 mm.
1.5 mm.
Potentilla subjuga
Potentilla brunnescens
Potentilla subjuga is centered in the high mountains of Colorado and barely enters New Mexico in the Sangre de Cristo Mountains. Collections from Alberta also apparently belong to this species, but all known collections from Wyoming have been identified as different taxa, at least one currently undescribed. At its most distinctive, P. subjuga is easily recognized by its unique leaf division, with five palmate leaflets subtended by an additional pair (or two) of lateral leaflets. Southern populations, however, are more likely to have only three apical leaflets. The leaflets tend to be strongly bicolored with overlapping teeth, in contrast to most sympatric pinnate species. Petiole vestiture is also distinctive in being seasonally dimorphic, with long hairs on first-formed leaves spreading to ascending and those on later formed leaves tightly appressed, as well as more conspicuously verrucose. Unresolved infraspecific variation exists, and field observations suggest that P. subjuga readily hybridizes with sympatric species, creating a swarm of intermediate specimens.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
The conspicuous golden glands, dark green color, and relatively broad leaflets make Potentilla brunnescens one of the better-defined species of sect. Graciles, though it has often been treated as a variety of P. gracilis. The glands, which are often on septate stalks, are particularly conspicuous on the epicalyx bractlets, hypanthium, and sepals, and at the junction of petiole and leaflets. The species occurs from the Blue Mountains of Oregon and Washington to western Montana, northern Utah, and north-central Colorado; collections from Alaska are probably not native.
As presented here, Potentilla brunnescens encompasses two morphological extremes that might merit varietal status. Leaflets of the more common and widespread extreme are incised about halfway to the midvein; in contrast, some populations in western Wyoming and adjacent Idaho have leaflets incised 3/4 or more to the midvein. The latter have often been assigned to P. gracilis var. elmeri while reserving P. gracilis var. brunnescens for the former; this is untenable because the type of P. brunnescens is the latter form.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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