Potentilla bipinnatifida
Potentilla nana
bipinnate cinquefoil, potentille bipinnatifide, tansy cinquefoil
arctic cinquefoil, dwarf cinquefoil
ascending to erect, (1–)2–5 dm.
ascending to erect, 0.1–0.5(–0.7) dm, lengths 1–2 times basal leaves.
subpinnate to subpalmate, (6–)10–25 cm;
petiole (2–)5–15 cm, long hairs dense, appressed, 1–2 mm, soft to ± stiff, short hairs absent, crisped hairs sparse, glands absent, sparse, or obscured;
leaflets 2–3 per side, on distal 1/6–1/3(–1/2) of leaf axis, separate to ± overlapping, terminal ones oblanceolate, (2–)3–6(–10) × 1–2(–3.5) cm, margins revolute, incised 3/4+ to midvein, undivided medial blade 1.5–6 mm wide, teeth 5–8 per side, ± linear, surfaces ± to strongly dissimilar, abaxial usually white, rarely grayish, long hairs abundant especially on veins, 1–2 mm, ± weak, short hairs absent or obscured, cottony (and crisped) hairs ± dense, glands absent or obscured, adaxial green to grayish, long hairs sparse to abundant, loosely appressed, 0.5–1.5 mm, short hairs absent or sparse, crisped and/or cottony hairs sparse to common, glands sparse to common.
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.
2–4.
(4–)10–50(–100)-flowered, congested or elongating in fruit.
1(–2)-flowered.
0.2–0.8 cm (proximal to 2 cm).
straight, 0.2–1.5 cm in flower, to 5 cm in fruit.
epicalyx bractlets narrowly elliptic to lanceolate, 2.5–6 mm, lengths ± 2/3 times sepals, margins flat;
hypanthium 3–5 mm diam.;
sepals 3–6 mm, apex ± acute, abaxial surfaces: venation indistinct, glands absent, sparse, or obscured;
petals yellow, 3–5 × 3–4 mm, lengths ± equal to sepals;
filaments 0.5–2 mm, anthers 0.3–0.5 mm;
carpels 50–80, styles papillate-swollen in proximal 1/2–3/4+, 1–1.2 mm.
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.
1–1.2 mm, smooth to faintly rugose.
1.4–1.6 mm.
= 56.
Potentilla bipinnatifida
Potentilla nana
Potentilla bipinnatifida is similar to P. litoralis in habit and leaf dissection but has flat, silky epicalyx bractlets and sepals with no evident glands. Vestiture is generally silkier, and the silvery to bicolor leaves are white-cottony abaxially. The two species are sympatric in the plains of Canada, with some intergradation; P. bipinnatifida is also common south to Colorado, where it is found in intermontane meadows and sagebrush flats. Outlying populations occur in Blaine and Custer counties, Idaho, and Duchesne and Piute counties, Utah. Eastern collections from disturbed sites might be adventive.
Potentilla missourica Hornemann ex Lindley and P. normalis Besser ex Sprengel are older names for this species; both were rejected against a conserved P. bipinnatifida with designated lectotypes (see J. Soják 2008b).
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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.)
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MI Flora
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