Potentilla nana
Potentilla morefieldii
arctic cinquefoil, dwarf cinquefoil
Morefield's cinquefoil
ascending to erect, 0.1–0.5(–0.7) dm, lengths 1–2 times basal leaves.
0.4–1.5(–1.7) dm, lengths 2–3 times basal leaves.
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.
pinnate, usually at least 2 pairs of leaflets separate from terminal leaflets, distal leaflets usually distinct, 2–6 cm;
petiole 0.2–1.5 cm, straight hairs abundant, ± appressed, 1–1.5 mm, stiff, cottony hairs absent, glands absent or sparse;
leaflets 5–9, on distal (1/4–)1/2–3/4+ of leaf axis, overlapping, proximal pair separated from others by 2–10 mm of leaf axis, central leaflets oblanceolate to narrowly obovate, (0.5–)1–2(–2.5) × 0.5–1.2 cm, petiolules 0–1 mm, distal 3/4 of margins incised 3/4 to midvein (sometimes medially cleft as well), teeth 3–4 per side, separate to slightly overlapping, (1–)2–5 mm, surfaces ± to strongly dissimilar, abaxial grayish to white, straight hairs ± abundant, ± appressed, 1 mm, weak to stiff (especially on veins), cottony hairs abundant to dense, glands absent or obscured, adaxial greenish to grayish, straight hairs ± abundant, appressed, 0.5–1.5 mm, stiff, cottony hairs absent, rarely sparse, glands sparse.
1(–2)-flowered.
3–15-flowered.
straight, 0.2–1.5 cm in flower, to 5 cm in fruit.
1–2.5(–3) 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 ± ovate-elliptic, 2–4 × 0.8–2 mm;
hypanthium 2.5–5 mm diam.;
sepals 3.5–5 mm, apex ± acute;
petals 4–6 × 3–5 mm;
filaments 1–2 mm, anthers 0.5–1 mm;
carpels 15–20, styles 2 mm.
1.4–1.6 mm.
1.5–2 mm, smooth to faintly rugose.
Potentilla nana
Potentilla morefieldii
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.)
Of conservation concern.
Potentilla morefieldii is known only from the White Mountains and adjacent Sierra Nevada. Plants with similar aspect but lacking strigose vestiture occur in White Pine County, Nevada; their disposition is uncertain. Potentilla morefieldii is sometimes confused with P. breweri (sect. Multijugae), but the latter differs in having more or less similar leaflet surfaces with cottony hairs nearly as abundant adaxially as abaxially. Potentilla breweri also lacks the stiff adaxial leaflet hairs that characterize most species in sect. Concinnae, including P. morefieldii.
W. L. Jepson (1909–1943, vol. 2) misapplied the name Potentilla pseudosericea var. grandiflora Th. Wolf, which is a synonym of an unresolved species from the Rocky Mountains (B. Ertter 1992; Ertter et al. 2013), to P. morefieldii.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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PNW Herbaria
WildflowerSearch
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USDA Plants Database
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