Potentilla bipinnatifida
Potentilla elegans
bipinnate cinquefoil, potentille bipinnatifide, tansy cinquefoil
elegant cinquefoil, silverweed
ascending to erect, (1–)2–5 dm.
erect, 0.1–0.5 dm, lengths 1–2 times 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, 0.5–2.5(–4) cm;
stipules: apex acute to obtuse;
petiole 0.2–1.8(–2.5) cm, long hairs ± sparse, ± spreading, 0.2–1 mm, weak, glands sparse to abundant;
leaflets 3, central obtriangular to flabellate, 0.5–0.7(–1) × 0.5–0.7 cm, petiolule 0–0.5 mm, margins flat, distal 3/4+ deeply 3–5-lobed (sinuses extending 2/3–3/4 to midvein), lobes unevenly incised 1/4–1/2 to midvein, teeth 1–3(–5) per lobe, surfaces similar, green, brownish, or reddish, hairs absent or sparse, 0.2–0.5 mm, glands sparse to common (also densely punctate-glandular).
2–4.
(4–)10–50(–100)-flowered, congested or elongating in fruit.
1-flowered.
0.2–0.8 cm (proximal to 2 cm).
straight or ± curved, 0–0.5(–2) 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 linear, elliptic, or obovate, 2–2.2 × 0.8–1.1 mm, margins flat;
hypanthium 2.5–3.5 mm diam.;
sepals 2.2–2.5 mm, apex broadly acute to obtuse;
petals pale yellow, 3–3.5 × 3–3.5 mm;
filaments 1–1.5 mm, anthers 0.3–0.4 mm;
carpels 20–25, styles ± columnar, not papillate-swollen proximally, 0.7–0.9 mm.
1–1.2 mm, smooth to faintly rugose.
1.2 mm.
= 56.
= 14, 28 (Russian Far East).
Potentilla bipinnatifida
Potentilla elegans
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.)
For present purposes, Potentilla elegans is treated in sect. Aureae, as was done by B. C. Johnston (1985), largely on the basis of pragmatism. J. Soják (1994) places the species instead in sect. Dumosae Soják, which otherwise comprises several Himalayan species.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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