Potentilla nana
Potentilla bruceae
arctic cinquefoil, dwarf cinquefoil
Bruce's cinquefoil
absent or inconspicuous, uncolored.
ascending to erect, 0.1–0.5(–0.7) dm, lengths 1–2 times basal leaves.
ascending to nearly erect, (1–)2–5(–6) dm.
not in ranks, ternate, 1–5 cm;
stipules: apex acute;
petiole 0.5–3.5 cm, long hairs sparse to abundant, ascending to spreading, 0.5–2 mm, ± soft, glands sparse to common;
leaflets 3, central obovate, 0.5–2 × 0.5–1 cm, petiolule 0–1 mm, margins revolute, not lobed, distal 1/2–2/3 evenly incised ± 1/2 to midvein, teeth 3–4(–6) per side, surfaces ± similar, green (paler abaxially), hairs sparse to abundant, 0.8–1.2 mm, glands sparse to common.
not in ranks, ± subpalmate to subpinnate (proximal leaflets sometimes doubled, distal leaflets confluent and/or decurrent), (2–)5–20(–28) cm;
petiole (1–)3–15(–20) cm, long hairs abundant, appressed to ascending-spreading, 1–2.5 mm, weak often flattened and twisted, sometimes grading to crisped or cottony hairs, short hairs absent, glands absent or sparse;
leaflets 5–7, on distal 1/10–1/4 of leaf axis, ± overlapping, largest ones usually ± obovate, (1–)1.5–5(–6) × 1–3.5(–4) cm, margins flat, distal 2/3–3/4 evenly to unevenly incised ± 1/2 to midvein (often with additional incisions nearly to midvein), undivided medial blade 4–20 mm wide, teeth (2–)3–6(–8) per side (sometimes secondarily toothed), ± lanceolate, 4–11 mm, surfaces ± similar, abaxial ± lighter and hairier, gray-green to grayish, rarely green, not glaucous, long hairs ± abundant, short-crisped hairs absent or sparse to common, cottony hairs usually absent, glands absent or sparse.
1–2.
1(–2)-flowered.
5–50-flowered.
straight, 0.2–1.5 cm in flower, to 5 cm in fruit.
0.5–3(–4) cm.
epicalyx bractlets oblong or ovate, 2.5–5 × 1.5–3.5 mm, margins revolute;
hypanthium 3–3.5 mm diam.;
sepals 2.5–5 mm, apex ± acute;
petals pale yellow, 4–8 × 4–6 mm;
filaments 1.2–2 mm, anthers 0.3–0.4 mm;
carpels 40–50, styles ± columnar, not or scarcely papillate-swollen proximally, 0.8–1.2 mm.
epicalyx bractlets broadly lanceolate to elliptic, 3–6(–7.5) × 1.5–2.5(–3) mm, hairs ± common to abundant, loosely appressed to ascending, glands absent or inconspicuous;
hypanthium 3.5–5.5 mm diam.;
sepals 5–10 mm, apex acute to acuminate;
petals 5–10 × 5–10 mm;
filaments 1–2.5 mm, anthers 0.7–1.2 mm;
carpels 15–30, styles filiform-tapered, papillate-swollen proximally, 2–3 mm.
1.4–1.6 mm.
1.4–1.6 mm.
= 63–73, 79, 87, 98, 129.
Potentilla nana
Potentilla bruceae
Potentilla nana has most often been considered a race of P. hyparctica or as the priority name for P. hyparctica. As now defined, P. nana occurs in an arc across southern Alaska, from the Aleutian and Pribilof islands to the Alaskan panhandle and adjacent British Columbia. T. Wolf (1908) treated it as a dwarf form of P. fragiformis; J. Soják (1996) interpreted P. nana as a hybrid species originating from cross(es) between P. fragiformis and P. hyparctica. Although the hybrid hypothesis has morphologic support, P. nana has a unique combination of morphologic features and has a distinct range from both P. fragiformis and P. hyparctica. The species are also ecologically segregated: P. nana is a coastal heath and gravel slope species, like P. hyparctica; P. fragiformis is strictly maritime coastal.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
As redefined by B. Ertter and D. Mansfield (2007), Potentilla bruceae is characterized by irregularly subpalmate, weakly villose leaves. Such plants form relatively consistent and extensive populations in dry meadows centered near Lake Tahoe in California and Nevada, extending to the central Sierra Nevada and to the Warner Mountains in Oregon. This interpretation differs from that previously suggested by Ertter (1992), in which P. bruceae was interpreted as the catchall category for hybrids between P. breweri (sect. Multijugae) and P. drummondii. All three taxa were accordingly treated as varieties of P. drummondii. D. D. Keck (in J. Clausen et al. 1940) treated P. bruceae as a subspecies of P. drummondii; B. C. Johnston (1980) concluded that its placement as a variety of P. breweri was more justified. The three entities unquestionably intergrade (with the type of P. anomalofolia M. Peck possibly one result), but not beyond what is the norm for facultatively apomictic species of Potentilla.
Chromosome numbers reported by J. Clausen et al. (1940) require verification as this species; the irregular behavior observed in meiotic material suggests that at least some of the individuals were hybrids.
See discussion of 29. Potentilla drummondii regarding leaflet dissection and the inclusion of P. bruceae in sect. Graciles.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
BC
PNW Herbaria
WildflowerSearch
iNaturalist
USDA Plants Database
CA
OR
Flora NW
